The skeptic does not mean him who doubts, but him who investigates or researches, as opposed to him who asserts and thinks that he has found.

An idea does not pass from one language to another without change.

Philosophy fulfills the need to create for ourselves a single and complete concept of the world and of life.

True science teaches, above all, to doubt and be ignorant.

Fear is the start of wisdom.

What is vanity but the longing to survive?

Faith which does not doubt is dead faith.