On Tuesday, March 19, 2013 3:26:49 PM UTC, Frederick Williams wrote: > quasi wrote: > > > > > > > > Yes, but the best teachers and authors have mastered the art of > > > judging how their presentation would be seen from the point of > > > view of the prospective student. > > > > While the lecturer knows to whom he is lecturing, the author of a book > > doesn't necessarily know who will read it. > > This seems exactly the wrong way round. A good maths book will specify exactly what the readership is expected to know -- "prerequisites" in other words. On the other hand, the abilities and knowledge bases of a graduate and undergraduate class can vary enormously, and it is difficult (but not impossible) to find out what they know.