Phronesis 63 (2018) 1-24

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Air as Noēsis and Soul in Diogenes of Apollonia

Rhodes Pinto
Department of Philosophy, Villanova University
800 Lancaster Avenue, Villanova, PA 19085. USA
rhodes.pinto@villanova.edu

Abstract

This article examines Diogenes of Apollonia’s doctrines of intellection (νόησις) and

soul in relation to his material principle, air. It argues that for Diogenes both intellec-
tion and soul are not, as commonly thought, some sort of air (namely, warm air), even
though both intellection and soul are to be understood in terms of air and the system
of τρόποι of air that he has set up. These new interpretations of intellection and soul
yield insight into Diogenes’ claims about the ordering activity of air as intellection and
a renewed appreciation for his material monism.

Keywords

Diogenes of Apollonia – soul – noēsis – air – principle – monism

1 Introduction

Despite coming at the end of the Presocratic period, Diogenes of Apollonia

is noteworthy for advancing a material monism. All things, according to
Diogenes, are air, which has different ‘modes’ or qualities (τρόποι) like hotter
/ colder, moister / drier, and swifter / slower moving. He also associates intel-
lection (νόησις) and soul with air, even claiming that air must have intellection
so as to order the world as it does. Scholarly reaction to his philosophy has
been mixed, though predominantly negative,1 while the precise details of his

1  Guthrie 1965, 381 calls his doctrines a ‘tour de force’, but negative reactions are more common,
e.g. Cherniss 1951, 344: ‘like the last meaningless twitchings of a broken habit, uncoordinated
repetitions of a pattern of past meaning;’ Barnes 1982, 567: ‘least as well as last.’

© koninklijke brill nv, leiden, 2018 | doi 10.1163/15685284-12341340

2 Pinto

monism have occasioned confusion and controversy from an early era. Indeed,
Simplicius furnishes us with the bulk of our extant fragments of Diogenes in
order to counter the understanding in Nicolaus of Damascus and Porphyry of
Diogenes’ ἀρχή as that which is between air and fire instead of air, which is how
Simplicius understands it.2 More recently, one vein of interpretation has been
to regard warm air, rather than air simpliciter, as basic, since it is this warm air
which scholars commonly regard as constituting both intellection and soul in
Diogenes’ philosophy.
In this article, I offer a critical re-examination of Diogenes’ accounts of in-
tellection and soul. All air, I argue, features intellection; the intellection of a
complex organism as a whole (such as a person) is a function of how well air
circulates through the veins of the body, for which moisture is the key deter-
mining factor. Soul, I argue, is a function of the temperature relation that the
(warmer) internal air has to the (cooler) external air when these airs come into
contact via respiration. The accounts of both intellection and soul thus utilise
τρόποι that Diogenes ascribes to air, but different ones, and they also invoke
air’s manner of interaction with more complex objects. It also emerges that
there is an equalising tendency to air’s τρόποι, which I suggest is an intelligent
act of air ordering the world in line with B3.3 Diogenes’ air monism, it turns
out, is hardly lacking in explanatory power.

2 Diogenes’ Air Monism

In order to understand Diogenes’ conceptions of intellection and soul, it is first

necessary to examine his physical theory.4 For he connects both soul and in-
tellection with his material principle, air. In the following fragment, Diogenes
appears to present a notion which closely resembles Aristotle’s description of
Presocratic material ἀρχαί at Met. 983b6-13: some underlying stuff from which
all things have come to be, into which they will revert, and of which they cur-
rently are (B2, from Simplicius, In Phys. 151.31-152.7):

2  Simplicius, In Phys. 25.8-9, 151.20-8 Diels. Aristotle (DA 405a21-22, Metaph. 984a5-7),
Theophrastus (Simplicius, In Phys. 25.4-6 = fr. 226A FSH&G, part), and Diogenes Laertius
(9.57) also understand it this way.
3  ‘A’ and ‘B’ references are to evidence for Diogenes (no. 64) in Diels and Kranz 1951-1952.
4  A full treatment of Diogenes’ physical theory is beyond the limited scope of this article. What
follows will merely offer an overview of Diogenes’ theory and touch upon some of the most
significant and relevant issues in its interpretation.

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Air as Noēsis and Soul in Diogenes of Apollonia 3

ἐμοὶ δὲ δοκεῖ τὸ μὲν ξύμπαν εἰπεῖν πάντα τὰ ὄντα ἀπὸ τοῦ αὐτοῦ ἑτεροιοῦσθαι
καὶ τὸ αὐτὸ εἶναι. καὶ τοῦτο εὔδηλον· εἰ γὰρ τὰ ἐν τῷδε τῷ κόσμῳ ἐόντα νῦν,
γῆ καὶ ὕδωρ καὶ ἀὴρ καὶ πῦρ καὶ τὰ ἄλλα ὅσα φαίνεται ἐν τῷδε τῷ κόσμῳ
ἐόντα, εἰ τούτων τι ἦν ἕτερον τοῦ ἑτέρου, ἕτερον ὂν τῇ ἰδίᾳ φύσει, καὶ μὴ τὸ
αὐτὸ ἐὸν μετέπιπτε πολλαχῶς καὶ ἡτεροιοῦτο, οὐδαμῇ οὔτε μίσγεσθαι ἀλλήλοις
ἠδύνατο, οὔτε ὠφέλησις τῷ ἑτέρῳ5 οὔτε βλάβη, οὐδ’ ἂν οὔτε φυτὸν ἐκ τῆς γῆς
φῦναι οὔτε ζῷον οὔτε ἄλλο γενέσθαι οὐδέν, εἰ μὴ οὕτω συνίστατο ὥστε ταὐτὸ
εἶναι. ἀλλὰ πάντα ταῦτα ἐκ τοῦ αὐτοῦ ἑτεροιούμενα ἄλλοτε ἀλλοῖα γίνεται καὶ
εἰς τὸ αὐτὸ ἀναχωρεῖ.

It seems to me, in sum, that all the things that exist are differentiated
from the same thing and are the same thing. And this is manifest. For if
those things which now exist in this cosmos (earth and water and air and
fire and as many other things as there manifestly are in this cosmos)—if
some one of these were different in its particular nature from another
and were not the same thing undergoing manifold changes and differen-
tiations, then in no way could they mix with each other, nor could there
be help or harm for another, nor could a plant grow from the earth or an
animal or any other thing have come to be, unless they were so composed
as to be the same thing. But all of these, which are differentiated from the
same thing, come to be different sorts at different times and revert back
into the same thing.

So, according to Diogenes, there is a ‘same thing’ (τὸ αὐτό) which all things are.
All things are also differentiated from this same thing (and indeed revert back
into it) while still being this same thing. Diogenes’ precise position, however,
remains difficult to formulate, all the more so when it was given before con-
cepts like ‘substance’, ‘matter’ or ‘essence’ had been established. One puzzle is
the phrase ἕτερον ὂν τῇ ἰδίᾳ φύσει and its relation to the counterfactual condi-
tion within which it is imbedded: ‘if some one of these (a) were different in its
particular nature from another and (b) were not the same thing undergoing
manifold changes and differentiations.’ What is contrary to fact? Is it just (b),
whereby each of these (earth, water, air, fire etc.) has its own particular nature,
or is it the combination of (a) and (b), whereby each of these share one par-
ticular nature? The syntax seems more inclined to the latter reading, while the
use of ἰδία with φύσις seems more inclined to the former reading. Still, the issue
strikes me as largely terminological. What is suggested by the uses of the verb

5  Diels adds <γενέσθαι ἀπὸ τοῦ ἑτέρου> after ἑτέρῳ. But the line is fully intelligible as transmit-
ted, even if highly compressed.

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4 Pinto

ἑτεροιοῦσθαι and by the use of ἀλλοῖα (with their -οι- component, like that
of the qualitiative pronominal adjectives, in contrast to ἕτερος and ἄλλος) is
that the sort of change that the ‘same thing’ undergoes is one of kind, affect or
quality. The basic idea thus can concisely be put as follows: everything is fun-
damentally the same thing, which can become different sorts. These different
sorts are the different-appearing things that we observe in the world.
Diogenes’ physical theory is further revealed in the first part of B5 (Simplicius,
In Phys. 152.22-153.4):6

καί μοι δοκεῖ τὸ τὴν νόησιν ἔχον εἶναι ὁ ἀὴρ καλούμενος ὑπὸ τῶν ἀνθρώπων, καὶ
ὑπὸ τούτου πάντα7 καὶ κυβερνᾶσθαι καὶ πάντων κρατεῖν· αὐτὸ γάρ μοι τοῦτο
θεὸς δοκεῖ εἶναι καὶ ἐπὶ πᾶν ἀφῖχθαι καὶ πάντα διατιθέναι καὶ ἐν παντὶ ἐνεῖναι.
καὶ ἔστιν οὐδὲ ἓν ὅ τι μὴ μετέχει τούτου· μετέχει δὲ οὐδὲ ἓν ὁμοίως τὸ ἕτερον τῷ
ἑτέρῳ, ἀλλὰ πολλοὶ τρόποι καὶ αὐτοῦ τοῦ ἀέρος καὶ τῆς νοήσιός εἰσιν· ἔστι γὰρ
πολύτροπος, καὶ θερμότερος καὶ ψυχρότερος καὶ ξηρότερος καὶ ὑγρότερος καὶ
στασιμώτερος καὶ ὀξυτέρην κίνησιν ἔχων καὶ ἄλλαι πολλαὶ ἑτεροιώσιες ἔνεισι
καὶ ἡδονῆς καὶ χροιῆς ἄπειροι.

And it seems to me that what has intellection is what is called ‘air’ by

men and that all things are steered by it and it rules all things. For this
itself seems to me to be a god and to reach into all and dispose all things
and be present in each thing, and there is nothing which does not par-
take in it. But one thing does not partake in it just as another thing does,
but there are many modes of air itself and of intellection. For it [air] is
multiform: hotter and colder and dryer and moister and more stationary
and having a swifter motion, and many other differences are present in it
unlimited in flavour and colour.

According to this fragment, air has many τρόποι, of which Diogenes mentions
heat, moisture and motion, using two comparative forms for each. These τρόποι
of air, I take it, are the ‘differentiations’ (ἑτεροιώσεις, matching ἑτεροιοῦσθαι in
B2) of what is the ‘same thing’. The passage accordingly maps air onto what
Diogenes speaks of as τὸ αὐτό in B2. He has smartly adapted the word τρόπος—
meaning ‘way’, ‘guise’, the ‘character’ of a person, or the ‘style’ of music or writ-
ing—for his notion of (what later thinkers might call) qualities or properties.

6  I am splitting B5, which is continuous in Simplicius, into two parts simply to facilitate easier
discussion of Diogenes’ doctrines. Most editors, it might be noted, tend to put a paragraph
break between these parts.
7  πάντα Panzerbieter, Schorn, Calogero: πάντας codd. See further Perilli 1988-89.

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Air as Noēsis and Soul in Diogenes of Apollonia 5

As Stokes well puts it, ‘if we have not reached the Aristotelian clarity of defini-
tion of substance and quality, we are here well on the road to it.’8
It is not entirely clear how many distinct τρόποι there are; the least tenden-
tious reading of B5 is that there are at least three of what I shall term ‘axes
of differentiation’—heat, moisture and motion. Each of these axes offers a
continuum of possible discrete values. Some scholars have attempted to col-
lapse these three axes into one axis9 or to make one axis primary.10 However,
Diogenes makes no such move explicitly. It is true that B5 gives particular at-
tention to heat (as it relates to soul), but that is not sufficient reason to suppose
that the axis of heat is privileged in his ontology. Indeed, as the following sec-
tion will make clear, he also gives particular attention to moisture (as it relates
to intellection).11 Nor does B5 explicitly mention condensation or rarefaction,
which numerous scholars have supposed to be an axis of differentiation for
Diogenes.12 Theophrastus does include condensation / rarefaction in a brief
summary cited by Simplicius: Diogenes ‘says that air is the nature of the all and
that this is infinite and eternal, since the form of the remaining things comes
to be from its being condensed and being rarefied and changing its quali-
ties (πάθη)’ (In Phys. 25.4-6 = A5). This report, however, has two issues which

8  Stokes 1971, 241. Theophrastus indeed uses πάθη for τρόποι in reporting Diogenes’ position
(quoted below).
9  So Heidel 1906, 377-9; Graham 2006, 285.
10  So Laks 2008a, 36; Graham 2010, 459.
11  Connected to the explication of the τρόποι in B5 is the abstruse καὶ ἄλλαι πολλαὶ ἑτεροιώσεις
ἔνεισι καὶ ἡδονῆς καὶ χροιῆς ἄπειροι. Is this meant to indicate that there are several more
axes (those for taste and colour), that there are an unlimited number of further axes,
that there are additional differences which derive from the differences of the three axes
given, or something else? For our purposes a speculative answer is not necessary; it will
be sufficient to say that there are at least three axes. It might be thought that taste and
(if hue-based) colour would not have axes as heat, moisture and motion do. However,
these could feature one axis for each primary colour or taste, each with a range from very
weakly present to very strongly present (akin to the sort of range given for motion). In
this manner other qualities that do not come in binary pairings could also be made into
axes. On any account, it is apparent that Diogenes is indicating that the three axes which
he has just presented are not themselves meant to be comprehensive of the differences
present in air. At the same time, the three axes which he specifically mentions are ones
which not only are most relevant for his other doctrines but also are most easily detected
in (atmospheric) air.
12  Included here are Zeller 1881, 291; Krause 1909-1915, (1) 236; and McKirahan 2010, 347. Some
scholars further suppose that it is the primary axis (McDiarmid 1953, 105; KRS [= Kirk et al.
1983] 444), and some even suppose that it is the sole axis (Heidel 1906, 377-9; Dockstader
2010).

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6 Pinto

strongly diminish its value as evidence. First, it presents air’s ‘changing its πάθη’
as a separate addition to its being condensed and rarefied. Condensation /
rarefaction would (if genuine) be one of the πάθη, which gives the mention of
condensation / rarefaction the strong impression of being Theophrastus’ own
addition. Secondly, according to Simplicius (In Phys. 149.32-150.1) Theophrastus
had said that only Anaximenes talked of condensation and rarefaction.
Simplicius’ claim here can be squared with Theophrastus’ report on Diogenes
if we suppose that condensation / rarefaction is Theophrastus’ own, added in-
terpretation of Diogenes (hence it is not something that Diogenes ever ‘talked
of’ himself). Condensation / rarefaction could easily have been read back into
Diogenes by Theophrastus (or even Aristotle). Aristotle claims that all of the
material monists made use of condensation / rarefaction to produce plurality,13
and it would have been particularly easy for Theophrastus to apply this rule
to Diogenes’ air monism given Anaximenes’ generation of other substances
via the condensation / rarefaction of air. Were condensation / rarefaction a
very important axis for Diogenes, as Theophrastus’ singling it out for mention
would suggest, then one would expect to find some specific mention of it in B5
or another of the extant fragments. But neither B5 nor any of the other extant
fragments speak to the condensation / rarefaction of air.14 Hence, it is prudent
to remain sceptical of the inclusion of condensation / rarefaction as an axis by
Diogenes. There are for Diogenes at least three axes of differentiation—heat,
moisture and motion (but probably not condensation / rarefaction)—no one
of which is primary, but each of which air features with a continuum of pos-
sible discrete values.

13  GC 330b7-13; Phys. 187a12-16. Aristotle’s claim is almost certainly an historically inaccurate
assumption given its lack of support in what we have of the material monists besides
Anaximenes and Heraclitus.
14  There are four apparent mentions of density in Diogenes’ philosophy: (1) his cosmogony
(according to A6) features a separation of the rare and dense via motion; (2) one of his
explanations of the limited intelligence of some living creatures is their density (as Aetius
in A30 phrases it, but cf. p. 12 below); (3) his explanation of the formation of sperm in B6
speaks of the ‘most thick (παχύτατον) blood’ and of what is left becoming ‘fine (λεπτόν)
and hot and foamy’; (4) his explanation of magnetism (according to Alexander in A33)
involves the magnet being both rarer (ἀραιοτέρον) and more earthy (γεωδεστέρον) than
iron. Particularly noteworthy is (4), which does not conform to the typical view of con-
densation / rarefaction, for the magnet is rarer yet more earthy. The position given in (4)
thereby suggests that condensation / rarefaction for Diogenes is an additional property
relating to the physical structure (spacing) within more complex things (i.e. composed of
one or more of the four ‘Empedoclean’ elements) and so is not an axis of air itself.

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Air as Noēsis and Soul in Diogenes of Apollonia 7

Diogenes’ tactic and insight in his physical theory is to recognise ranges of

qualities (the τρόποι) that his stuff can hold, which allows everything to be the
same thing while still granting enough difference to account for the multitude
of things in the world and for all of their motions and changes. Fire, earth and
water, which (along with air) receive mention as an explication of ‘the things
now in the cosmos’ in B2,15 all are forms of air that differ in its qualities (i.e. its
values along the axes of differentiation)—they are different sorts of air (cor-
responding to ἀλλοῖα in B2). In other words, each of these has its own determi-
nate range of values on the axes within which it must fall. While they are all still
the same thing—air—each nevertheless is something in the world that can be
referred to and invoked.16 Other objects may not be solely constituted by the
particular values of each of their axes: B2’s subsequent appeal to the need for
the things now in the cosmos to mix and to help and harm is suggestive of a
doctrine of a set of stuffs—the four Empedoclean elements mentioned—that
together compose (note the use of συνίστατο in B2) and foster more complex
things like plants and animals.17
Admittedly, in B5 Diogenes does state that by ‘air’ he means what people
commonly recognise and refer to as air (ὁ ἀὴρ καλούμενος ὑπὸ τῶν ἀνθρώπων),
and according to Simplicius he spoke likewise within a later discussion on
blood vessels (In Phys. 153.16-17).18 It is not entirely clear how Diogenes can
make such a claim, for it seems that on his account air should be, to borrow

15  Added to these four is ‘and as many other things as there manifestly are in this cosmos’.
This final component could either be meant to cover all other objects or to cover any
other proposed primary bodies. It is possible that the mention of all four Empedoclean
elements—including air—in this counterfactual protasis prompted the (mistaken)
understanding of Diogenes’ ἀρχή in Nicolaus of Damascus and Porphyry as that which
is between air and fire, since they took it to preclude any of these from being his ἀρχή.
Diogenes’ invocation of heat in regard to air in B5 (or any similar passage), which I will
examine in detail in Section 4 below, could also have played a major role in occasioning
their understanding.
16  Cf. A16: fire is the cause of lightning and thunder; A31: there is air in water for fish to
breathe; A32: plants come to be by water putrefying and mixing with earth; A33: the mag-
net is more earthy than iron. Note also that Diogenes is content in both B2 and B5 to speak
of coming to be, with four uses of forms of γίγνομαι between them. B7 also speaks in terms
of coming to be (γίνεται) and perishing (ἀπολείπει). Hence Diogenes’ notion of ‘different
sorts’ is strong enough that he feels entitled to speak of these ‘sorts’ with the language of
coming to be and perishing.
17  For Diogenes, of course, they would not be elements in the strict sense since they are
non-basic.
18  Hence Barnes 1982, 576 contends that Diogenes’ ἀρχή is not air but undifferentiated
matter, ‘sōma’.

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8 Pinto

some later terminology, a sort of material substratum. I suggest that Diogenes

has not fully completed the process of separating substance and qualities (as
Aristotle would later do). He thinks that atmospheric air is air in its ‘default’
state, a state where the values of the τρόποι are in their natural or undisturbed
state, like the centre position on a balance scale. In other words, the ‘same
thing’ is most closely associated with a certain set of qualities (i.e. certain val-
ues for the τρόποι): those with which we humans have associated what we call
‘air’. Diogenes could thereby feel entitled to suppose that all things are air while
at the same time supposing that all (other) things are differentiated from air
and indeed will revert back into air. It is worth noting too that Diogenes never
directly claims that all things are air; in B5 he claims that all things ‘partake in’
(μετέχει) air and that air is ‘present in’ (ἐνεῖναι) every thing, which seem appro-
priate ways of expressing that all things have qualitative differences from what
is fundamentally the same thing yet is best or most naturally or most closely
expressed as atmospheric air. Hence also he feels entitled to use the neuter
forms of the personal and demonstrative pronouns to refer to air—which oc-
curs most notably in B2 (which does not speak of ‘air’ at all), as well as in B4,
B7, B8 and possibly B5—for his understanding of air is in fact broader than the
atmospheric air of contemporary usage.
What Diogenes does in establishing air as his material principle is to in-
voke what he calls τρόποι, the qualities of air that comprise everything, to ac-
count for the diversity of things in the world. There are at least three of these
τρόποι—heat, moisture and motion—each with its own continuum. These can
accordingly be thought of as the axes of differentiation for air; different values
for these τρόποι make for different sorts of things (at least for the level of the
Empedoclean elements). As will become evident in the following two sections,
Diogenes invokes the τρόποι, and more specifically differences in them, to ac-
count for phenomena like soul and intellection in creatures.

3 Air as Intellection

Air for Diogenes is more than just the material principle of all things. In B5,
Diogenes claims that air is what has intellection (τὸ τὴν νόησιν ἔχον), and sim-
ilarly in B8 he claims that ‘it’—presumably air—knows many things (πολλὰ
εἰδός). Indeed, Simplicius appears to have taken the argumentative burden
of Diogenes’ work not to be that air is the ἀρχή but rather that the ἀρχή has
‘much intellection’ (In Phys. 151.29-30). Immediately striking is that Diogenes
uses νόησις instead of (as Anaxagoras notably had) νοῦς, the activity instead of
the faculty. By invoking an activity rather than a faculty possessed, Diogenes

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Air as Noēsis and Soul in Diogenes of Apollonia 9

can avoid any potential issue of the faculty being (or being of) some stuff other
than air. His choice of νόησις also ensures that air is engaging in the activity
of intellection, whereas νοῦς (‘mind’ or ‘intelligence’) might or might not be
engaging in the activity. Much as air, as the material principle, has certain
properties or qualities (the τρόποι)—including most notably motion, which
can loosely be regarded as another kind of activity—air also has the activity
of intellection.19
Why Diogenes might want to stress the activity of intellection becomes
clearer in another fragment, where he offers an argument for air having intel-
lection (B3 = Simplicius, In Phys. 152.12-16):

[Diogenes] says: ‘for, without intellection, it would not be able to have

been distributed20 in such a way that it has the measures of all things—of
winter and summer, of night and day, and of rainy weather and winds
and calm weather. And the remainder, if one wants to consider it, one
would find ordered in the finest possible way.’

For Diogenes, the world displays order; indeed, it is ordered in the finest pos-
sible way. The active operation of intellection is required to order the world by
ensuring the correct distribution of air, namely that those things determined
by its differentiations—objects comprised of air, as well as the τρόποι of air
itself—are in appropriate measure. More specifically, as I will argue in Section
5, this involves the balancing or equalising of proportions and provides for
change, life and a habitable world. Since all things are air, the intelligent direc-
tion cannot come (as in Anaxagoras) from a distinct, separate party. By having
the activity of intellection,21 air is always able to direct its changes and motions
in a way that produces order. There is thus a cosmic role to the intellection that
air features. There is also a more localised role, as air also serves as intellection
(and soul) for humans and animals (B4 = Simplicius, In Phys. 152.18-21):

19  Indeed, just as there are τρόποι for air, according to Diogenes there are many τρόποι to
the intellection that air has. It is somewhat unclear what Diogenes intends by this claim.
Τρόποι in the case of νόησις could be different sorts of thought or perhaps different levels
of intelligence that intellection exhibits. It is also possible that he means that νόησις can
by extension be regarded as having the very τρόποι that air has since air is what possesses
νόησις.
20  Or ‘to have distributed itself’, should we press a middle reading of δεδάσθαι.
21  Presumably along with possessing knowledge, as B8 claims.

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10 Pinto

Further, besides these, there are also the following great signs. For both
men and the other animals in breathing are alive by means of air. And
this is both soul and intellection for them (as will be clearly shown in this
work), and if this has departed, they die and [their] intellection fails.

Given that soul is distinguished from intellection here (καί … καί ...), there is
presumably a difference in their functions. Since the failure of intellection
(ἡ νόησις ἐπιλείπει) surely corresponds to the prior presence of intellection,
death presumably corresponds to the prior presence of soul. Thus death would
be something distinct from an organism’s sudden failure of intellection. Still, it
cannot be that Diogenes simply thinks that soul is what, when present, makes
one alive. For the Greek for ‘alive’ is ἔμψυχον, which would make for an unhelp-
ful, circular position. So what, then, might the presence of soul in an organism
do such as to make it ‘alive’? Intellection is ruled out, as has just been noted,
by the distinction made in B4 between it and soul.22 Initiating motion thus
becomes the obvious answer, a position which can be paralleled in Diogenes’
predecessors and contemporaries.23 B4 may thereby be taken to suggest that
Diogenes regards soul as what enables a thing to initiate some motion for itself,
such as the moving of its limbs. Since air, specifically its intake via breathing, is
requisite for living things’ ability both to initiate motion (and thereby for their
life) and to exercise their intellect,24 Diogenes strengthens his more general
understanding of air as motive and noetic.
Does Diogenes mean that the air which living things breathe itself consti-
tutes their soul and intellection? Scholars commonly take the second part of
B5 to indicate that differences in heat constitute differences in intelligence

22  Aristotle does claim that for Diogenes the soul knows (γινώσκειν, DA 405a23 = A20).
However, it seems clear from the context of Aristotle’s preceding and following remarks
that it is Aristotle’s own inference—from the positions that the soul is air and that air
knows—that the soul knows.
23  The association between soul and the initiation of motion is already present in the phi-
losopher traditionally recognised as the first of the Presocratics, Thales (on which, see
Pinto 2016). Indeed, Aristotle takes the initiation of motion to be one of the two major
characteristics of soul found in his predecessors (DA 403b25-9). Besides Thales, Aristotle’s
account of his predecessors reveals this association—in a way which does not seem
purely interpretative on Aristotle’s part—in Democritus (DA 404a1-9, 405a8-13), certain
Pythagoreans (404a16-19), and Alcmaeon of Croton (405a29-b1, which is supported by
further testimonia grouped under 24 A12 DK), to whom Plato’s discussions of the soul as
a mover in the Phaedrus and Laws 10 clearly owe some debt.
24  Marine creatures are no exception; Aristotle reports that Diogenes held that they breathe
air that is dissolved in the water (A31).

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Air as Noēsis and Soul in Diogenes of Apollonia 11

for living things. Scholars have accordingly put qualifications on the claim
that air is intellection,25 qualifications which call into question whether air
simpliciter is his ἀρχή (B5, part = Simplicius, In Phys. 153.4-13):26

καὶ πάντων τῶν ζῴων δὲ ἡ ψυχὴ τὸ αὐτό ἐστιν, ἀὴρ θερμότερος μὲν τοῦ ἔξω
ἐν ᾧ ἐσμεν, τοῦ μέντοι παρὰ τῷ ἡλίῳ πολλὸν ψυχρότερος. ὅμοιον δὲ τοῦτο τὸ
θερμὸν οὐδενὸς τῶν ζῴων ἐστίν (ἐπεὶ οὐδὲ τῶν ἀνθρώπων ἀλλήλοις), ἀλλὰ
διαφέρει μέγα μὲν οὔ, ἀλλ’ ὥστε παραπλήσια εἶναι. οὐ μέντοι γε ἀτρεκέως γε
ὅμοιον οὐδὲν οἷόν τε γενέσθαι τῶν ἑτεροιουμένων ἕτερον τῷ ἑτέρῳ, πρὶν τὸ αὐτὸ
γένηται. ἅτε οὖν πολυτρόπου ἐούσης τῆς ἑτεροιώσιος πολύτροπα καὶ τὰ ζῷα
καὶ πολλὰ καὶ οὔτε ἰδέαν ἀλλήλοις ἐοικότα οὔτε δίαιταν οὔτε νόησιν ὑπὸ τοῦ
πλήθεος τῶν ἑτεροιώσεων. ὅμως δὲ πάντα τῷ αὐτῷ καὶ ζῇ καὶ ὁρᾷ καὶ ἀκούει,
καὶ τὴν ἄλλην νόησιν ἔχει ἀπὸ τοῦ αὐτοῦ πάντα.

The soul of all animals is the same thing, too: air which is warmer than the
outside air in which we are yet is much colder than the air around the sun.
And this heat is the same for no two animals (for it is not even the same
comparing individual humans). The difference is not great but is such
that they are similar. Indeed, no one of those things which are differenti-
ated is able to become exactly like another without becoming the same
thing. Since, then, the difference is multiform, living things are multiform
and many and not like each other in appearance, way of life, or intel-
ligence because of the multitude of the differences. Still, all things live
and see and hear by means of the same thing, and all things have overall
intellection27 from the same thing.

25  E.g. McDiarmid 1953, 105: ‘intelligence is a form of air;’ Guthrie 1965, 369: ‘it is natural to
infer from fr. 5 that the purest form of air, which is sheer intelligence and God, is warmer
than that which gives life and less perfect powers of cognition to the animals and our-
selves;’ KRS 444: ‘intelligence is warm air;’ McKirahan 2010: 348: ‘warm air is the cosmic
intelligence.’ Betegh 2004, 310 gives two possible options: ‘(a) the air as such is intelligence,
but it is the intelligence of living beings when it is in the specified range of temperature, or
(b) the temperature of air qua intelligence in general must be within this range, therefore
also when it functions as cosmic intelligence,’ although he shows a slight preference for (a).
26  So e.g. KRS 439 n. 1: ‘Perhaps we should suppose that atmospheric air is not the basic form
of air, but a close derivative. The basic form of air is presumably the warm air that is in-
telligence … if, that is, Diogenes distinguished any such “basic” or true form.’ In a slightly
different vein, Laks 2008b, 357 entertains the suspicion that the ‘original form’ of air was
hot air.
27  Τὴν ἄλλην νόησιν presumably highlights the contrast with νόησιν in the prior line, where it
was spoken of as regards its individuality (i.e. as being different for different living things).

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However, Theophrastus’ extended report of Diogenes’ theory of perception

in the De sensibus (A19) includes an explanation of difference in intelligence
that utilises not heat but moisture: ‘Thinking (φρονεῖν), as was said, is by the
pure and dry air. For moisture hinders the intellect’ (De sens. 44). According
to Theophrastus, Diogenes uses moisture to explain both the greater intelli-
gence of humans compared to animals and the fluctuations of an individual’s
intellect (why it is lower when one is asleep, drunk or full of food). Animals
are set lower to the earth and so ‘breathe the air from the earth’; they also eat
moister foods (ib.). Presumably it is likewise for individual humans: in sleep
one lies closer to the earth where one breathes in moister air, while food and
drink are all rather moist. Theophrastus’ report also presents a second, relat-
ed component for explaining some differences of intelligence: how well the
air can permeate throughout the body. Birds are less intelligent since the air
cannot permeate through their entire body but stops at their stomachs (ib.).28
Children are less intelligent since they are moister, which blocks the air from
spreading beyond their chests (45). Diogenes evidently also deploys this sec-
ond component to explain those things which do not demonstrate any intel-
ligence: ‘plants utterly lack thought (τὸ φρονεῖν) because they are not hollow
and so do not admit air’ (44).29 Presumably, this claim would apply not only to
plants but to the multitude of (apparently) unintelligent objects, for instance a
marble statue: it is not hollow and so does not admit of outside air.
Invoking hollowness to explain the presence or absence of intelligence does
not appear well-considered; what, for instance, about seemingly unintelligent
bronze statues? ‘Hollowness’, I suggest, is an oversimplification or misunder-
standing of Diogenes’ doctrine on Theophrastus’ part. What Diogenes actually
supposes is that for an object to engage in intellection air must not merely
permeate but must circulate. What is not hollow cannot have circulation of
air, but even some hollow things, like a bronze statue, have no facility for the

According to Theophrastus (De sens. 40), Diogenes took seeing and hearing to be forms of
αἴσθησις (not νόησις), so I do not think that τὴν ἄλλην νόησιν could mean ‘the rest of νόησις’.
28  Theophrastus mentions a further component (for birds): the shape of their tongue and
mouth is such that they cannot communicate with each other.
29  This position notably contrasts with that of Anaxagoras, who claimed that plants have
intellectus and intellegentia (cf. [Aristotle], De plantis 6.17-18 Meyer). Despite the presence
of mind (νοῦς) and intellecting air throughout the world in the respective philosophies
of Anaxagoras and Diogenes, these philosophers differ in the extent of the objects in the
world they suppose to possess intelligence. With his doctrine of circulation, Diogenes
may be viewed as having worked out a clever way of restricting intellection among com-
plex objects to those widely agreed to possess it, one in line with his apparent interest,
evidenced by B6, in the human vascular system.

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Air as Noēsis and Soul in Diogenes of Apollonia 13

circulation of air and so do not intellect. We know from a preserved, extended

treatment regarding the vascular system (B6) that Diogenes had great interest
in the veins, and there is solid evidence that he invoked veins as the structure
for circulation. Indeed, the circulation likely involves air mixing with the blood
in the veins. According to Theophrastus: ‘he attributes perceiving, pleasure and
thinking to the mixture of blood with breathed-in air (ἀναπνοή)’ (De sens. 47; cf.
43). Similarly, Simplicius claims that Diogenes said that ‘intellections (νοήσεις)
come to be from air with blood embracing (λαμβάνων) the whole body via the
veins’ (In Phys. 153.14-15). Veins are hollow passages, so it would be easy to mis-
take their hollowness as the primary point rather than the circulation of air
that their hollowness allows. Both moist air and the moisture in food or drink
prevent the mixture from circulating as it should in the veins, thereby hinder-
ing intellection. Diogenes’ underlying notion is presumably that moist air is
capable of slowing or clogging these hollow cavities (veins) through which air
circulates. The complete lack of intellection is simply an extreme case: when
there is no circulation whatsoever.
The need for circulation within a hollow body (i.e. one having veins) would
fit well with Diogenes’ emphasis in B4 that living things are breathing; air, after
all, might still be permeating a dead body. Thus the act of breathing is itself an
important condition, as it provides for the circulating flow of air throughout
the body. Differences in degree of circulation (i.e. throughout the whole body
or through only part of the body), which are based on moisture, are responsi-
ble for differences in intelligence.30 The complete cessation of circulation is re-
sponsible for the complete loss of intellection. Absence of the structure (veins
or the like) needed for circulation is responsible for absence of intelligence.
There is more than a glimmer here of Plato’s doctrine in the Timaeus and Laws
10 that intelligence or reason is a sort of (or is analogous to) circular motion,
with increasing deviation from the circularity of the revolution corresponding
to poorer intelligence or reason.
One might have thought that Diogenes’ position would need to be that all
things engage in intellection, including plants and statues whether of marble
or bronze. For the ‘air’ that has intellection in the first sentence of B5 is (as I in-
dicated earlier) the subject of the next sentence, where it is said to be present
in every thing and that nothing fails to partake in it. The manner of partaking,
namely the many τρόποι (of air), is then discussed in the next two sentences.
The implication is thus that air, regardless of the state of its τρόποι (which are

30  Perhaps differences in intelligence between individual members of the same species are
caused by how well the air permeates each particular body, or perhaps some individuals
are just a little moister or drier than others.

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14 Pinto

responsible for delimiting at least the four Empedoclean elements, of which

everything else would be composed), has intellection. Accordingly, the par-
ticular heat and moisture values of air do not preclude intellection per se, and
air (no matter how moist or how cold) can thereby possess the intellection
requisite for providing order to the world. Why, then, do plants and statues,
which are comprised of air, not have intellection? I suggest that what is at stake
here is whether some object taken as a whole (e.g. the plant or the human or
the statue) has intellection. Every bit of the plant (as air) possesses intellec-
tion, but for the plant, unlike humans and animals, there is no structure (veins
or the like) such that, via the circulation of atmospheric air, there could be a
singular process of intellection for the plant as a whole. Those objects (taken
as a whole), like a human, which do posses intellection possess it in virtue of
the circulation of respired air through their structure (body). Air itself does not
need to circulate for it to feature intellection; as the first line of B5 indicates, air
has intellection. It has intellection regardless of its heat, moisture or its circu-
lation. But for something non-basic and indeed complex the circulation of air
is required. The air runs through or, as it were, ties together the whole object.
This allows there to be a singular process of intellection for the object as a
whole and further allows for there to be a range of intelligence to this process
of intellection in virtue of the extent of circulation. It is precisely because air
has intellection that there is a need to invoke something else, such as circula-
tion, to account for why some complex objects feature intellection and others
do not.

4 Air as Soul

As I argued in the previous section, Diogenes invokes soul for life and there-
by for the motions that some things initiate for themselves. Having perhaps
noticed that respiration ceases at death or that forcibly stopping respiration
induces death, Diogenes appeals in B4 to the intake of air not only for intel-
lection but also for soul. One might have expected that the air which things
breathe would be the air which comprises soul, but in B5 Diogenes instead
claims that ‘the soul of all animals is the same thing, too: air which is warmer
than the outside air in which we are yet is much colder than the air around
the sun’. What are we to make of this claim in B5? The standard reading is that
soul is warm air.31 Let me instead suggest that the key lies in the comparison

31  So e.g. Zeller 1881, 292-3; Krause 1909-1915, (3) 326; Burnet 1930, 358 (with the addition ‘cir-
culating with the blood in the veins’); Cherniss 1935, 54 n. 215; KRS 444; McKirahan 2010,
348. Some refer to ‘hot’ air instead of ‘warm’ air, but the sense is the same.

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Air as Noēsis and Soul in Diogenes of Apollonia 15

offered between the temperatures of the airs. Soul is not simply warm air; it is
air that bears a certain temperature relation to the surrounding atmospheric
air. More specifically, it is a difference in which the heat of the internal air is
somewhat warmer than the outside air but not so warm as is the air around the
sun. If one feels a living body or the air it exhales, it seems natural to conclude
that the body’s internal air is of such a (somewhat warmer) temperature. It is
this difference itself which furnishes an organism with the ability to initiate its
own motions.
Adding a further detail—that along with the difference in temperature the
internal air and the external air must interact or come into contact—can ef-
fectively explain life and death. Diogenes’ embryology supports this detail.
According to Aetius (5.15.4 = A28), ‘Diogenes [says] that foetuses are begotten
without life (ἄψυχα) but in heat (ἐν θερμασίᾳ). Whence as soon as the foetus
is delivered, it32 draws the innate heat into its lungs.’ According to ps.-Galen’s
account (Hist. phil. 119), it is instead ‘the cold’ which is drawn into the lungs.
Ps.-Galen’s version is probably to be preferred on this point, although it is cer-
tainly possible that Diogenes thought that the innate heat of the body is drawn
to the lungs where it warms the colder air that has been breathed in. I take
these reports to indicate that a baby starts being alive and having soul at the
very moment it starts breathing, the moment when the colder outside air en-
ters into the warmer (i.e. heat-having) body and they interact, resulting in the
drawn-in air becoming warmer (than the external air).33 It is thus no surprise
that Diogenes particularly associates the warmer, internal air with soul in B5.
In the unborn foetus there is no true difference in heat as the foetus is not
yet interacting with the outside air; hence it is ἄψυχον. Diogenes’ explanation
might have continued: if respiration ceases, that creature dies (can no longer
initiate any motions), since the internal air and the external air no longer come
into contact with each other, eliminating the difference that is productive of
motion. Humans and animals are always fighting a losing battle, as they are
trying to stay warmer than their outside environs. They gradually cool off, mak-
ing it certain that at some point the warmth of their internal air will reach an
equalisation to the outside air (or will fall below a certain threshold such that
the difference is no longer great enough to produce motion). Then they will

32  This corresponds to the transmitted text. Diels (not noted in DK, but noted in Diels 1879)
adds τὸ ψυχρὸν after τοῦ βρέφους (‘the innate heat draws the cold into its lungs’) on the
basis of ps.-Galen.
33  Or, looking at it a different way (one in less close keeping with the phraseology of B5),
the internal heat becomes cooler. Ψυχή for Diogenes might be aligned with the sense of
ψυχοῦν. His position can be compared with Philolaus (44 A27 DK), who focuses on the
need to breathe for cooling the heat of the body.

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cease to breathe and, no longer having soul, die.34 Such cooling would account
for ‘natural’ deaths (i.e. those without any apparent precipitating cause). Other
circumstances which forcibly stop the process of respiration would account
for other deaths.
Soul thus belongs only to those creatures that respire and have this particu-
lar difference in heat—and belongs to them only for so long as they do.35 A
difference with respect to the outside air neatly explains how a creature both
gains and eventually loses its ability to initiate its own motions. There is thus
nothing intrinsic to warm air that allows for the production of motion. It is
rather that the air which comprises soul is air that is in the right sort of relation
to its environment—a relation of a certain difference between the value of its
heat-axis and the value of the heat-axis of the atmospheric air external to it.
Hence air is not itself soul nor does it itself have soul; rather, air(s) in a certain
relationship provide for soul in certain complex objects.36
My interpretation avoids several serious difficulties that arise under the
standard interpretation—according to which Diogenes’ concept of soul in-
vokes the intrinsic nature of warm air. The standard interpretation runs as
follows: before being born, humans and animals have no (atmospheric) air
within their bodies and hence are ἄψυχον; it is only once they start breathing
that atmospheric air enters into the body, where it is warmed by the innate
heat of the body to a sufficient degree to provide for motion. But why, then,
should the cessation of respiration cause the death of a creature? Even if an
animal is not breathing in any fresh atmospheric air, the previously-inhaled

34  Hence the explanation which Aristotle attributes to Diogenes for why fish die when taken
out of the water: they draw in too much air (A31). A large intake of air will cool off the
internal heat of the fish very quickly, eliminating the difference.
35  Plants would accordingly not have soul. Evidently Diogenes accounted for the genera-
tion (and, the present considerations would lead one to assume, growth) of plants via
the putrefaction of water and its mixture with earth (A32). That doctrine is perhaps the
reason for the distinction found in B2: οὐδ’ ἂν οὔτε φυτὸν ἐκ τῆς γῆς φῦναι οὔτε ζῷον οὔτε
ἄλλο γενέσθαι οὐδέν. Regarding plants as not having soul hardly appears to be an excep-
tional position in the Presocratic period. Plutarch, for instance, elects to note how the
Anaxagoreans and Democriteans (as well as the Platonists) suppose that a plant is an
‘en-earthed animal’ (ζῷον ἔγγειον, Quaest. phys. 911D). That Plutarch feels the need to offer
such a note may be taken to suggest that this is the atypical view on plants and thereby
that the more common view is that plants are not ζῷα and so do not have souls.
36  This reveals another reason for Diogenes to invoke something like circulation for the pos-
session or lack of intellection in complex objects: he could not have claimed that only
what is alive (i.e. what has soul) possesses intellection, because this would exclude air,
which does not have soul, from possessing intellection as he supposes it must (B3).

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Air as Noēsis and Soul in Diogenes of Apollonia 17

warmed air (that constituted soul) might still be supposed to be present. Why
need an animal breathe more than one first time? Also, if warm air is soul,
and all things are air, why does the embryo not have soul? (I.e. why must soul
require warm atmospheric air?) One way of resolving these difficulties would
be to suppose that the body is too hot to produce motion, and the (continual)
intake of cooler air is required to achieve the heat range suited to the produc-
tion of motion.37 Another (not necessarily competing) way would be to sup-
pose that soul is not simply warm air but is the circulation of warm air in a
body. Atmospheric air is the sort of air that can circulate through the body.
Circulation, I concluded earlier, is a requirement for objects to engage in in-
tellection. On this account, the cessation of respiration stops the manner by
which the air is circulated, leading to death. Soul would not simply be warm
air; it would be air that interacts with the organism to become appropriately
warm and perhaps then to circulate through the body.38 However, in examin-
ing intellection we found that Diogenes holds that animals and children do
not have the air circulate throughout their entire body (hence their lower in-
tellection). Even if one supposes that the circulation needed for soul is not
throughout the body but rather only through part of the body, it hardly seems
appropriate to suppose that animals and children are less motive than adult
humans. Even worse, if we follow a line of reasoning strictly parallel to the
account of intellection, they would be less ensouled and less alive. Otherwise
one would have to make an unattractive and seemingly arbitrary distinction
so that degrees of the circulation of air produce degrees of intellection but not
degrees of soul / motion.
Again, if soul is warm air (whether circulating or not), what makes this
warm air more apt to produce an organism’s motion? One might suppose that
motility was simply linked to the heat axis of differentiation (i.e. hotter = more
motive), but these τρόποι appear to be presented in B5 as distinct from each
other. Invoking the difference of heat—between the outside air and the inter-
nal air—avoids this problem, as well as provides an explanation for why some
humans and animals simply stop breathing and die.
Admittedly, Aristotle reports that for Diogenes air is soul (DA 405a21-5 =
A20). However, it would be easy to misconstrue Diogenes’ nuanced doctrine
of soul, especially when others took soul to be air simpliciter. Indeed, Aristotle
here says: ‘Diogenes, just as certain others too, air.’ Even on the standard in-
terpretation of Diogenes’ theory of soul (warm air), Aristotle provides a poor

37  Such was the interpretation of Diller 1941, 373.

38  This account, it might be noted, seems no closer to the remarks of B5 then my preferred
account.

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report since he omits any mention that the air which is soul is warm. The
reason which Aristotle gives for Diogenes’ selection of air—‘supposing that
this is the rarest of all (λεπτομερέστατον) and the principle’—also casts some
doubt on the reliability of the report. The mention of rarity does not square
with Diogenes’ understanding of air’s τρόποι. For should condensation / rar-
efaction be an axis, air would feature all degrees of density. Difficulty remains
even if Aristotle meant ‘atmospheric air’, since fire / aether ought to be rarer
than atmospheric air.39 It is also no help if we understand λεπτομερέστατον as
‘finest-particled’; there is no evidence whatsoever that Diogenes held a par-
ticulate view of stuffs, and one would expect fire to be finer-particled than air.
Moreover, the position which Aristotle attributes to Diogenes bears an alarm-
ing resemblance to Democritus’ theory of spherical soul atoms which Aristotle
had just mentioned (403b31-404a9, 405a10-13). Aristotle, unable to tease out
Diogenes’ understanding of soul but aware of Diogenes’ claims that air was
intellection and the basic stuff, may simply have assumed that he offered a
similar explanation to Democritus (cf. 405a8-11), an explanation which fits into
Aristotle’s framework for understanding his predecessors in this chapter of the
De anima (cf. 403b24-8, 404b27-8, 405a3-7).40
Perhaps more problematic for my interpretation is Aetius’ report: ‘and if all
of the airy nature (ἀερῶδες) should leave the veins, death occurs’ (5.24.3 = A29),
along with his inclusion of Diogenes among those who say that the soul is in-
destructible (4.7.1 = A20).41 It may be that Aetius conflated the explanation of
intellection in animals with that of death. Laks offers another good explana-
tion: ‘La doxa … tire la conséquence de la réduction aristotélicienne de l’âme à
l’air en général, et donc au principe indestructible’ (2008a, 129). Indeed, Aetius

39  Krause simply felt that the difficulty was ‘ein fundamentaler innerer Widerspruch’ on the
part of Diogenes (1909-1915, (2) 380-3).
40  For a similar account of Aristotle’s report, see Laks 2008a, 127.
41  The former report is perhaps not too problematic on its own. It is simply vague, not ex-
panding on ἀερῶδες, which could mean air that is warmer than the outside, as per my
interpretation of soul and death. Even if it means that all the air that had been mixed with
the blood in the veins leaves, that would still be compatible with how I am suggesting
soul be understood in Diogenes. For no air in the veins means that there cannot be the
appropriate relation between the (now non-existent) internal air and the external air, and
hence such a creature would have no soul and be dead. Note that such an account lacks
any obvious reason or mechanism for the air leaving its mixture with the blood and the
veins (and therefore for death—the account would provide a how, not a why), unlike my
suggestion of death stemming from the internal air cooling down until a point of equali-
sation with the outside air.

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Air as Noēsis and Soul in Diogenes of Apollonia 19

additionally attributes to Diogenes (together with Cleanthes and Oenopides)

the view that there is a world-soul (1.7.17 = A8). Diogenes’ principle (particu-
larly as presented by Aristotle, with air being soul and ἀρχή) readily invites
conflation with Stoic doctrine.
There is evidence which aligns with my interpretation. In two other
instances, Diogenes can be found to invoke some difference between two ob-
jects with respect to one of the τρόποι in explaining certain motions. In both
of these cases, just as I am suggesting for soul, there is an inclination to the
equalisation of these differences which is productive of motion.
As Alexander of Aphrodisias relates Diogenes’ explanation of magnetic at-
traction (Quaest. 2.23 = A33), Diogenes thought that malleable things (i.e. met-
als / metallic rocks) emit and draw in from outside a certain moisture (ἰκμάς:
presumably a sort of moist air or imperceptibly small units of water), and
that how much they emit and draw in depends on what sort they are (Quaest.
p. 73.11-13 Bruns). Iron (along with bronze) emits the most moisture (73.13). The
magnet, which is looser-textured (ἀραιότερον) and more earthy (γεωδέστερον)
than the iron, draws in more moisture than it emits (73.18-20). Further, the
magnet attracts and draws into itself only the moisture which is συγγενές to
it, and that of the iron is συγγενές to it (73.20-4). So the magnet has a sort of
difference in moisture, attracting more than it emits. As to the iron, the trans-
mitted text awkwardly states that the iron draws in more moisture than the
magnet.42 The underlying thought would presumably be that the iron has an
ample supply of emitted moisture that the magnet can draw in. However, such
a position faces difficulty for why the iron does not attract magnets or anything
else.43 I tentatively suggest that Diogenes’ actual claim about the iron, which
ended up garbled in Alexander, was that the iron emits more moisture than it
absorbs.44 Therefore the iron’s own emissions more than supply its absorption

42  τοῦ σιδήρου ἕλκοντός τε καὶ πλεῖον ἀφιέντος ὑγρὸν τὴν λίθον οὖσαν ἀραιοτέραν τοῦ σιδήρου καὶ
γεωδεστέραν πλεῖον ἕλκειν τὸ ὑγρὸν τὸ ἀπὸ τοῦ παραακειμένου ἀέρος ἢ ἀφιέναι (‘while the
iron both draws in and emits more moisture [than the magnet?], the magnet … draws in
more moisture from the surrounding air than it emits’) (73.17-20). Note that the participial
clause (referring to the iron) lacks the comparison suggested by ἕλκοντός τε καὶ πλεῖον
ἀφιέντος ὑγρόν and that the comparison shifts in the main clause: πλεῖον ἕλκειν ἢ ἀφιέναι.
43  Alexander’s report goes on to claim that the iron is not so rare (ἀραιόν) as to be able to
receive the moisture of the magnet en masse (ἀθρόαν); hence, the magnet is not attracted
by the iron (73.24-5). Alexander himself objects that there is no reason to suppose that
a thing’s attractive power would be any less if it cannot receive the moisture into itself
despite drawing it to itself (73.30-74.4).
44  In other words, what I am suggesting is that Diogenes’ original text featured for
Alexander’s participial clause a comparison parallel to the ἕλκειν / ἀφιέναι comparison

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needs, so that it does not attract anything else to itself.45 Diogenes is setting
up a second-order difference between the emission / absorption difference
of the magnet and the emission / absorption difference of the iron. With one
thing (iron) emitting more moisture than it draws in, and the other (magnet)
drawing in more moisture than it emits (and the moisture being compatible),
when they are close enough together the difference draws the former to the
latter.46 These differences are permanent, which is why magnetic attraction
always behaves the same way. Presumably, other metals and stones simply do
not have an emission / absorption disparity or else have a very weak one, so
that they draw in no moisture besides what they themselves emitted and have
little extra emitted moisture for something else to draw in.
An additional instance of a difference creating motion comes in Seneca’s
report on Diogenes’ hydrology (Natural Questions 4a.2.28-30 = A18). Seneca re-
ports (as a direct quotation) that for Diogenes the sun first draws moisture to
itself, then the dried-out land draws moisture from the sea, and finally the sea
draws moisture from other waters. The details of the explanation are particu-
larly suggestive of the fact that the difference in moisture itself drives a cor-
rective, redistributive motion: ‘when the earth has become dried up, it draws
more moisture to it. Just as the oil in a lamp flows to where it is burned up, so
too water inclines itself to where the force of the heat and the burning earth
summon.’ The attracted water flows through certain passageways in the Earth,
passageways which likewise drain off excess water. Not only did Diogenes
use this to explain how the sun has not managed to dry out the Earth com-
pletely, but he also used it to explain the flow of the Black Sea always to the
Mediterranean (29). So it appears that Diogenes invoked a difference in mois-
ture, either its excess or deficiency, as what is responsible for moving quanti-
ties of water to equalise the difference.

in his main clause. We should understand the position as if Alexander wrote τοῦ σιδήρου
πλεῖον ἀφιέντος ὑγρὸν (‘while the iron emits more moisture [i.e. than it draws in], the mag-
net … draws in more moisture from the surrounding air than it emits’). A scribe predating
Alexander (or even Alexander himself) could have been confused by Diogenes’ com-
pressed Greek and misconstrued the text. Alternatively, ἕλκοντος could have been written
above πλεῖον ἀφιέντος as a gloss to explain the omitted comparison and later fell into the
text.
45  The iron thus has limited available void-space, which would fit with what Alexander re-
lated (see above n. 43) as the explanation of why the iron does not attract the magnet.
46  Following the transmitted text, the difference is simply that the magnet absorbs more
moisture than it emits (and the iron emits a lot of moisture).

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Air as Noēsis and Soul in Diogenes of Apollonia 21

Regarding soul for Diogenes to be the air within a body that features a tem-
perature difference (moderately warmer) to the air outside the body when they
come into contact via respiration thus best corresponds to both the evidence
and the philosophical demands upon his position. Diogenes does not need to
invoke soul for things besides humans and animals, for air is itself (more or
less) motive and its other τρόποι can also be invoked to explain motion.47 A
sort of unity of explanation of motion—the τρόποι of air—has been achieved
without granting soul (and thereby life) to all things which initiate some mo-
tion for themselves.

5 Conclusions: Air as Explanation

Diogenes is an air monist. All things are fundamentally air but are different
sorts in virtue of the modifications to air’s qualities (τρόποι): at least heat,
moisture and motion, each of which can take on particular values along a
continuum of possible values. All air possesses intellection, thus granting it
the intelligence to direct and organise itself (i.e. the world). The structures
of complex objects—and how these interact with the τρόποι of air—account
for whether these objects have intellection (and their degree of intelligence)
and whether these objects have soul. Intellection of some composite whole
is a function of the circulation of respired air through its body, a circulation
which can be hindered by moisture. Soul is a function of the difference in tem-
perature that the (warmer) internal air has to the (cooler) external air when
they interact via respiration. That difference is what allows for the initiation
of motion, just as differences involving τρόποι do in his preserved accounts of
magnetism and hydrology.
More specifically, the accounts of soul, magnetism and hydrology rely
upon differences in the values of a τρόπος and what appears to be an inher-
ent inclination for these differences to equalise.48 Why is there this equalising

47  One might contrast Diogenes’ position with that of Thales, who invoked soul for magnets
(11 A22 DK) and probably, as I have elsewhere argued (Pinto 2016), for all things that initi-
ate some motion.
48  While there is no direct evidence, it seems reasonable to suppose that this equalising in-
clination applies generally to the τρόποι. For example, if I pour cold water into a hot mug,
the water and the mug become warm. Such occurrences, particularly with temperature
and moisture, are easily observed. The system of the τρόποι that Diogenes sets up thus
offers a straightforward way of accounting for qualitative change.

Phronesis 63 (2018) 1-24

22 Pinto

inclination? An intriguing, if speculative, possibility is that he regards this

equalising inclination as a noetic operation of air ordering the world. In other
words, the equalising inclination is an expression of air’s best-possible order-
ing of the world. Intellection, Diogenes would suppose, is required to equalise
things: to recognise what would amount to a balanced distribution. Attributing
such a view to Diogenes has the compelling advantage of providing a much-
needed cause for this equalising inclination while also helping to account for
the claim argued in B3 that air must have intellection. The equalisation being
an intelligent activity of his ἀρχή, air, would fit well with the language in B3 of
air as ‘being distributed’ or ‘distributing itself’ (δεδάσθαι). Moreover, the prin-
ciple having the ‘measures of all things’ (also B3) could refer to its compre-
hending and equalising the proportions present between things. Admittedly,
the examples that B3 gives for having the measure of all things—winter and
summer, day and night, bad weather and good weather—certainly do not ex-
hibit any apparent inclination toward equalisation; instead, there is simply a
balanced distribution of each.49 However, these examples need not be seen as
opposed to the ordering of differing proportions through their equalisation.
Rather, they can be viewed as complementary; the examples given, which are
on a larger scale than that of τρόποι, simply evidence how air as intellection
has a grasp of proportion and balance and brings it to bear on the world so that
it is ordered in the finest possible way. As air has the measure of all things, it
recognises the sort of ordering needed: whether there should be balanced dis-
tributions of things that are different (that are not inclined to equalisation, like
good weather and bad weather) or whether there should be an equalisation
of the difference (as in the instances of hydrology, magnetism and soul—all
cases directly involving one of the τρόποι of air). What this ordering produces
is life (soul) and world capable of supporting it, as well as a regular and struc-
tured system of qualitative change (as per n. 48 above) and locomotion. Thus it
would be an act of air’s intellection, ordering the world in the best possible way
given its understanding of the ‘measures’ of all things, that causes the equalisa-
tion of difference central to Diogenes’ account of soul, as well as his accounts
of magnetism and hydrology.
So, even if Diogenes ‘returns’ to material monism by postulating some one
basic stuff, it is a deliberate philosophical decision, one which advances and

49  The seasons are of approximately equal length. So too are night and day. Bad weather and
good weather are in a balanced proportion such that plants grow. Were these factors not
balanced as they are, plants, animals and humans would be unable to survive.

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Air as Noēsis and Soul in Diogenes of Apollonia 23

refines the understanding of how a material monism could function to explain

motion and change, the (orderly) world, and life.50

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