If you can't explain it simply, you don't understand it well enough.

圖片引自http://www.brandautopsy.com/2012/03/albert_einstein_knowledge.html

今天在台大物理系看到一個postdoc的電腦上放了這句話, 深表贊同

If you can't explain it simply, you don't understand it well enough.

Albert Einstein
(German born American Physicist who developed the special and general theories of relativity. Nobel Prize for Physics in 1921. 1879-1955)