Nature never deceives us; it is we who deceive ourselves.

The indifference of children towards meat is one proof that the taste for meat is unnatural; their preference is for vegetable foods...Beware of changing this natural taste and making children flesh-eaters, if not for their health's sake, for the sake of their character; for how can one explain away the fact that great meat-eaters are usually fiercer and more cruel than other men; this has been recognised at all times and in all places.

My bad head cannot adjust itself to the way things are.... If I want to depict spring, it has to be in wintertime; if I want to describe a beautiful landscape, I must be enclosed within walls; and I have said a hundred times that if I were put in the Bastille, there I would paint a picture of liberty.

Chemistry... is like the maid occupied with daily civilisation; she is busy with fertilisers, medicines, glass, insecticides ... for she dispenses the recipes.

At Genoa, the word Liberty may be read over the front of the prisons and on the chains of the galley-slaves. This application of the device is good and just. It is indeed only malefactors of all estates who prevent the citizen from being free. In the country in which all such men were in the galleys, the most perfect liberty would be enjoyed.

If Socrates died like a philosopher, Jesus Christ died like a God.

We do not know what really good or bad fortune is.