O love, if I regret the age when one savors you, it is not for the hour of pleasure, but for the one that follows it.

Conscience is the voice of the soul, the passions are the voice of the body. Is it astonishing that often these two languages contradict each other, and then to which must we listen? Too often reason deceives us; we have only too much acquired the right of refusing to listen to it; but conscience never deceives us; it is the true guide of man; it is to man what instinct is to the body; which follows it, obeys nature, and never is afraid of going astray.

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.

Girls must be thwarted early in life.

It is believed that physiognomy is only a simple development of the features already marked out by nature. It is my opinion, however, that in addition to this development, the features come insensibly to be formed and assume their shape from the frequent and habitual expression of certain affections of the soul. These affections are marked on the countenance; nothing is more certain than this; and when they turn into habits, they must leave on it durable impressions.

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

Those people who treat politics and morality separately will never understand either of them.