一个学生曾向古希腊哲学家芝诺求教:“老师,您的知识比我多许多倍,对问题的回答又十分正确,可是您为什么总是对自己的解答有疑问呢?”芝诺没有直接回答学生的问题,而是顺手在桌上画了一大一小两个圆圈,并指着这两个圆圈说:“人的知识好比一个圆圈,圆圈里面是已知的,圆圈外面是未知的。你知道的越多,圆圈就越大,不知道的也就越多。这就是我常常怀疑自己的原因。” One student once asked Zeno, the ancient Greek philosopher: “Teacher, your knowledge is many times better than me, and the answer to the question is correct, but why do you always have questions about your answer?” “Zeno Rather than answering questions directly to the students, Ralph Lauren pas cher, but easily painted a big two small circles on the table, pointing to the two circles and said: ”Human knowledge is like a circle, inside the circle is known, outside the circle Is unknown, the more you know, the bigger the circle, and the more I do not know.This is why I often doubt myself. "