René Descartes

Reason is nothing without imagination, but imagination does not imply reason, it appears.

Nihil sub sole novum, as it says in the Bible.

(There is nothing new under the sun)

A bit of the old on the internet no-one knows you’re a dog, I think. Therefore I am a webdev dog too.

How do we know that the thoughts which occur in dreaming are false rather than those others which we experience when awake, since the former are often not less vivid and distinct than the latter?

Doubt is the origin of wisdom.

How can you be certain that your whole life is not a dream?

It is a mark of prudence never to place our complete trust in those who have deceived us even once.

Reading good books is like engaging in conversation with the most cultivated minds of past centuries who had composed them, or rather, taking part in a well-conducted dialogue in which such minds reveal to us only the best of their thoughts.

Common sense is the most widely shared commodity in the world, for every man is convinced that he is well supplied with it.

An optimist may see a light where there is none, but why must the pessimist always run to blow it out?