The secret of good teaching has resisted both psychological and sociological analysis. Yet every student knows that teachers differ and most students, if only from sentiment and tradition, admit to at least one teacher who influenced them greatly. Pressed to describe this influence, students use such words as “inspiring” or “stimulating,” or they say: “He got me going, I started to work.” The investigator receiving such answers feels tantalized and stymied: something is going on but he doesn’t know what.