The senses deceive from time to time, and it is prudent never to trust wholly those who have deceived us even once. – Rene Descartes
Each problem that I solved became a rule, which served afterwards to solve other problems. – Rene Descartes
The two operations of our understanding, intuition and deduction, on which alone we have said we must rely in the acquisition of knowledge. – Rene Descartes
Nothing is more fairly distributed than common sense: no one thinks he needs more of it than he already has. – Rene Descartes