People demand freedom of speech to make up for the freedom of thought which they avoid. (Soren Aabye Kierkegaard)

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

It is much more comfortable to be mad and know it, than to be sane and have one’s doubts. (G. B. Burgin)

His ignorance is encyclopedic (Abba Eban)