If you are looking for a biography of Voltaire, I suggest you look further for many reasons. First, his philosophies really aren't explained well in this film other than his views on religious tolerance and liberty. Second, it only covers a tiny portion of his later life during the last years of the reign on Louis XV. And, third, the film really isn't intended as a history lesson but, like so many biopics of the era, strays rather far from the facts. Still, George Arliss was a fine actor, and I'd recommend any film in which he appears.
The story is about a tiny portion of Voltaire's life--when he takes up the cause of a specific man who was convicted on scant evidence and who was simply the victim of religious bigotry. And, the film consists of Voltaire scheming, very cleverly, to influence the fat-headed king to intervene and overturn the verdict. First, he writes a play which parodies the situation--changing the facts a bit but making the point which Voltaire wishes to put across to the king. Second, he enlists the help of the king's #1 babe, Madame Pompadour to get the king to offer Voltaire a chance to put on the play at Versailles. But, things backfire--can the wily Voltaire manage to extricate himself? I must let you know that I am generally not a big fan of costume dramas--mostly because they often come off as a bit stilted and stodgy. This one isn't as bad as many but it all the fine costumes and language did seem, at times, a bit stiff. Not bad at all--but it also seemed a bit preachy and unreal--especially Voltaire's crazed speech at 71 minutes into the film. Plus, the film jumped from the early 1760s to 1789 almost instantly--making it look as if Voltaire DIRECTLY initiated the French Revolution!!
By the way, I am not sure if the film would have been made after mid-1934, as the new Production Code cleaned up films--removing anything that might be objectionable. In some ways, this was strongly needed (as ANYTHING seemed to go in films in the early 30s). But, in others it over-sanitized things--and biopics on men of such liberal views on the Church and conventional morality as Voltaire were difficult sells in the new 'cleaner' (at least on the surface) Hollywood.