笑对人有益，只要不出人命就好。

"What's terrible is to pretend that second-rate is first-rate. To pretend that you don't need love when you do; or you like your work when you know quite well you're capable of better."

Play is the language of childhood, and books should speak that language too.

Leadership in agriculture means having the courage to plant seeds whose harvest you may never see.

清白的良心是一个温柔的枕头。

在数学中，坚持往往比才华更重要。