Just a quick reference. In a short set of essays on writing mathematics by Paul Halmos and others, Halmos pointed out that central to his pedagogy with the use of spiraling for communicating a set of ideas. That is, he would present the idea in the first part, reintroduce it in a different form in the second part, ect., until completion. More- over, he claims that he has written all of his books in this manner; i.e., write the first chapter, the rewrite the first chapter. Write the second chapter, then rewrite the first and second chapters. Write the third chapter, then rewrite the first, second and third chapters, etc.. So here the method of spiraling underlies the structure of his book as well. This is what he started doing when he wrote his first book (Set Theory).
How did he start doing this ? I don't recall what he wrote, if anything. But he did note that John von Neuman wrote and lectured this way (Halmos was his assistant as a young post doc).
Al BArron email@example.com have a good weekend!