Any great scientist will pitch his course to the graduate student level, no matter how hard he tries not to. The ''Physics Today'' RichardFeynman tribute issue referred to this as the ''FeynmanEffect''. The article explained that for every undergraduate who dropped Feynman's course, another grad student or professor sat in on it, so that he might not have known that the undergrads were leaving. Still, the Feynman Lectures are the best textbooks of the 20th century. There's nothing like them.

''That tale has grown in the telling, but these volumes certainly seem to fail as freshman courses (other institutions have tried them). The lectures are not the greatest physics books of the 20th century. They are overall an interesting introduction, but they are a bit hit and miss. Volume three isn't very good, but the first two both have bright moments. There are some very good physics books published last century, perhaps most not at an elementary level. There are gems like Landau and Lifshitz ''The Classical Theory of Fields'' (ISBN 0750627689) which can't be dismissed so easily. Goldstein's ''Classical Mechanics'' (ISBN 0201657023) is also a gem.''

Its worth noting that, based on my experience, judging the quality of his books by their success with a freshman physics class is a pretty useless measure. More than half of the students in the freshman physics course I took failed, and the course somehow acquired a reputation as incredibly difficult... without straying outside of the topics we'd covered in our high school physics courses by more than a couple of minor topics.

''Except that his books (the lecture notes ones anyway) were intended to be for freshman physics classes, so it's a reasonable measure in this case''

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When I was a physics undergrad, we also referred to a "Feynman Effect", slightly different from the above (but maybe a consequence of it): certain lecturers presented material (especially QM) to us in an exciting, dynamic way, a way that rekindled our passion for the subject, and a way which seemed utterly clear at the time; but when it came to review our notes of the lectures, a way which made ''absolutely no sense''. This term inspired by the same effect occurring whenever the Red Books were consulted.

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Seems to remind me of an anecdote attributed to Einstein. It went like this: Einstein is standing up in front of a big big big blackboard he just covered in math. He was just presenting the problem, noting it down on the blackboard, then writing out all the rest saying, as he reached the end: "See?". Agitated whispering on the tiers. Finally a student scrapes up all his courage and says something like, "Um, ... would you awfully mind explaining the way to this solution to some of us in more detail?" Einstein gracefully complies by wiping the blackboard for all but the presentation of the problem, scratches his head, writes all the rest back on again, and turns back to the student saying, "See? It's as easy as that."