I do not hesitate to claim the good fortune of having stumbled, in my youth, upon certain paths which led me to certain considerations and maxims from which I formed a method of gradually increasing my knowledge and of improving my abilities as much as the mediocrity of my talents and the shortness of my life will permit. ... I spent a few years of my adolescence traveling, seeing courts and armies, living with people of diverse types and stations of life, acquiring varied experience, testing myself in the episodes which fortune sent me, and, above all, thinking about the things around me so that I could derive some profit from them. ... The greatest profit to me was, therefore, that I became acquainted with customs generally approved and accepted by other great peoples that would appear extravagant and ridiculous among ourselves, and so I learned not to believe too firmly what I learned only from example and custom.

-- Rene Descartes, Discourse on Method