The magic ingredient of teaching, I think, is the teacher's love of the subject matter. If the discipline is important, if the intellectual approach to the subject is exciting and demanding and insightful, if there is much work waiting to be done, then the teacher cannot help being full of enthusiasm and inspiration. With enough of that, only a perverse act of will could insulate a student from instant intellectual stimulation. This is both good and bad news. Bad news because love and enthusiasm are hard to acquire if you don't have them. Good news because if you do have the bug, it is easy to learn to flaunt it, to spread it around, and to infect others with it.

At Berkeley I teach two types of courses and two types of students. I regularly teach a large introductory course in economics or American economic history, my particular field. These are large lecture courses with 300 to 500 students, sometimes 800 students. But I also teach graduate student specialists in small seminar settings and in one-on-one discussion. The large lectures attract students as often as not because the course is required or prerequisite rather than interesting a priori. The graduate students, of course, are already committed to the field and are learning to be masters in their own right. Yet I've found that both types of students are surprisingly responsive to enthusiasm.

Undergraduates are awakened and aroused by the instructor's belief in the subject. By introducing a student to a new mode of thinking or a new subject matter, an instructor can change a student's life. This process of turning on someone else's thinking and enthusiasm is itself exciting, and it also feeds on itself. I come with some excitement for the subject. I show students my delight. I think out loud in front of them. To them it is a new way to think. They become excited. I become more excited. They become more excited. In the end they learn. They learn a lot. They remember.

The graduate students, too, although trained to be skeptical of the theory and findings of their discipline and long over the first blush of enthusiasm and well into the drudgery of unglamorous research, are not immune to the instructor's enthusiasm. It reminds them that their field is worth all the hard work. It rekindles their inspiration. This process, too, is circular. Their willingness to undertake hard work, their excitement with new discoveries, and their eagerness recharge the teacher. And the teacher carries that energy back to the undergraduates. Teaching graduate students is a most valuable part of the process of teaching undergraduates well. That is why Berkeley works so well.

Here is my advice: Don't teach if you don't like the subject matter. If you love it, don't hide it. Wear your zeal on your sleeve, shout it, show it, sing it. The rest will take care of itself.