The better students, moreover, are at the better schools. Most important scholars I have know received their training at major graduate schools, no matter how ordinary their undergraduate education. On the other hand, many extremely promising undergraduates must go to the lesser graduate centers, because of personal circumstances, ignorance of their quality, better financial aid, or whatever. Why have so few of these latter students succeeded in research? After all, the material that is taught in the major graduate centers is in print and available everywhere. My explanation is that in the leading graduate centers the students learn primarily from one another. They learn to impose higher standards upon themselves, both in the selection of problems to work on and in the adequacy of the solutions they provide to these problems. Bull sessions are a more effective method of teaching and learning than classroom lectures or discussion. One colleague has said that he considered his role in the classroom to be that of providing topics for bull sessions. I don't think that the successes achieved by the graduates of the major schools are due simply to an old-boy network. Anyone who does outstanding work is in strong demand even if, like the hypothetical mathematician I referred to, he has few other redeeming traits. -- George Stigler, Memoirs of an Unregulated Economist