Descartes constructed as noble a road of science, from the point at which he found geometry to that to which he carried it, as Newton himself did after him. ... He carried this spirit of geometry and invention into optics, which under him became a completely new art.
People must have renounced, it seems to me, all natural intelligence to dare to advance that animals are but animated machines.... It appears to me, besides, that such people can never have observed with attention the character of animals, not to have distinguished among them the different voices of need, of suffering, of joy, of pain, of love, of anger, and of all their affections. It would be very strange that they should express so well what they could not feel.
The little may contrast with the great, in painting, but cannot be said to be contrary to it. Oppositions of colors contrast; but there are also colors contrary to each other, that is, which produce an ill effect because they shock the eye when brought very near it.
What will the preachers say? .. to teach men not to persecute men: for, while a few sanctimonious humbugs are burning a few fanatics, the earth opens and swallows up all alike.
It is the poverty connected with our species which subordinates one man to another. It is not inequality which is the real misfortune, it is dependence.