Each problem that I solved became a rule which served afterwards to solve other problems. (Rene Descartes, Discours de la Methode)

The optimist proclaims that we live in the best of all possible worlds, and the pessimist fears this is true. (James Branch Cabell)

All are lunatics, but he who can analyze his delusion is called a philosopher. (Ambrose Bierce)

The power of accurate observation is frequently called cynicism by those who don’t have it. (George Bernard Shaw)

I do not feel obliged to believe that the same God who has endowed us with sense, reason, and intellect has intended us to forgo their use. (Galileo Galilei)