笛卡爾旅行的結果，覺得在此國以為神聖的事，在他國卻視為下賤；在此國以為大逆不道的事，在別國卻奉為天經地義，因此他覺悟到貴賤善惡是因時因地而不同的。他認為從前積下來的許多觀念是不可靠的，因為他們多是趁他思想幼稚的時候侵入來的。如若欲過理性的生活，必得將從前積的的知識，一件一件用懷疑的態度去評估他們的價值，重新建設一個理性的是非。這懷疑的態度，就是他對對於人生與哲學的貢獻.——哲學與人生

After Descartes’s travels, he felt that what was considered sacred in this country was regarded as inferior in other countries, and what was regarded as treacherous in this country was regarded as the righteousness in other countries. Therefore, he realized that whether they are noble or bad, good or evil depend on a concrete time and place. He believed that the ideas which were accumulated in the past were unreliable. If you want to live a rational life, you must use the knowledge accumulated from the past with a skeptical attitude to evaluate their value, and rebuild a rational points of right and wrong. This skeptical attitude is his philosophy.——Philosophy and Life