Psychology must be based on facts, not hypotheses.
如果使人们喜怒无常,居处不定,思虑不得要领,行事中途就乱了章法;那么,天下间就会出现各种不平与不合理,而后像盗拓或者曾参、史鳅做的那些事情,都会发生。
I don't have any particular recipe [for developing new proofs] ... It is the reason why doing research is challenging as well as attractive. It's like being lost in a jungle and trying to use all the knowledge that you can gather to come up with some new tricks, and with some luck you might find a way out.