I have no definite philosophy of teaching, but after more than thirty years of experience I have learned a few things, most of them quite obvious.

The first and most important is that if one is to explain something clearly, one must first understand it.

The second is that students should be vigorously encouraged to play an active rather than passive role in their own education. Over the last thirty years I have observed among Berkeley students (especially undergraduates) an unfortunate and increasing tendency toward passivity, the desire to be "entertained." This may have something to do with the pervasiveness of television. It is regrettable that we occasionally pander to this tendency by rewarding teaching that is essentially nothing but show business. Perhaps we do this out of defensiveness to the repeated accusation that the Berkeley faculty ignores undergraduate teaching.

The last has to do with the training of graduate students in research. In my view, the most effective way to do this is by example, from day to day. I try to work together with my research students on perplexing questions and unsolved problems, and I do not like to ask them to undertake anything in the laboratory, however arduous, that I am not prepared to do myself. I like to think that in my laboratory they may learn general values, such as intellectual honesty, perseverance, and courage in the face of adversity, as well as specific technical and professional skills.