"David C. Ullrich" wrote: > > On Tue, 19 Mar 2013 08:38:20 -0700 (PDT), email@example.com wrote: > > >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. > > ??? There are _official_ prerequisites for a class. A student is not > _allowed_ to take this class without having passed those other > classes. All the author of a book can do is explain what audience > he had in mind - he has no control over who actually reads the book.
That's what I was thinking. When I was a student prerequisites were not (or not always) carved in stone: a lecturer might say 'course XYZ is a prerequisite unless you are willing to do a lot of work reading up on ABC during the first week.' But the effect was similar.
Also, with a book, if the reader finds himself out of his depth after the first two chapters, he can put it down, read something of a more introductory nature and then pick it up again. One can't do that with a lecture course.
-- When a true genius appears in the world, you may know him by this sign, that the dunces are all in confederacy against him. Jonathan Swift: Thoughts on Various Subjects, Moral and Diverting