Work keeps us from three great evils, boredom, vice and need.

Doubt is uncomfortable, certainty is ridiculous.

Doubt is not a pleasant condition, but certainty is absurd.

I advise you to go on living solely to enrage those who are paying your annuities. It is the only pleasure I have left.

Four thousand volumes of metaphysics will not teach us what the soul is

When he to whom one speaks does not understand, and he who speaks himself does not understand, that is metaphysics.

Originality is nothing but judicious imitation. The most original writers borrowed one from another.