This mother needs happy, reputable children, and that one needs unhappy ones: otherwise she cannot show her kindness as a mother.

The drive toward knowledge has a moral origin.

In certain pious people I have found a hatred of reason, and have been favourably disposed to them for it: their bad intellectual conscience was at least exposed by that!

Science and art have that in common that everyday things seem to them new and attractive.

Every man has his price. This is not true. But for every man there exists a bait which he cannot resist swallowing. To win over certain people to something, it is only necessary to give it a gloss of love of humanity, nobility, gentleness, self-sacrifice - and there is nothing you cannot get them to swallow. To their souls, these are the icing, the tidbit; other kinds of souls have others.

Pardon me, my friends, I have ventured to paint my happiness on the wall.

One may sometimes tell a lie, but the grimace that accompanies it tells the truth.