To enjoy a book... I find I have to treat is as a sort of hobby and set about it seriously. I begin by making a map on one of the end leafs; then I put in a genealogical tree or two; then I put a running headline at the top of each page; finally I index at the end all the passages I have for some reason underlined. I often wonder-how people enjoy themselves developing photos or making scrapbooks-why so few people make a hobby of their reading in this way. Many an otherwise dull book which I had to read have I enjoyed in this way, with a fine nibbed pen in my hand: one is making something all the time, and a book so read acquires the charm of a toy without losing that of a book.
I think re-reading old favourites is one of the things we differ on, isn't it, and you do it very rarely. I probably do it too much. It is one of my greatest pleasures: indeed I can't imagine a man really enjoying a book and reading it only once.
Perhaps people don't make their books their own in Lewis's way because they respect them too much. Still, it is a good idea to keep an index of the passages you have marked (in whatever way) as significant. It could be made in light pencil on the fly leaf or even on a separate index card (or cards) that you keep in the book. Transferring the notes (or at least the index) into your electronic note-taking file is not a bad idea either. I nowadays try to do just that!
To re-read some books is good, too. Though I disagree with those who claim that the only books worth reading are those that you would wish to re-read. Apart from the fact that it is difficult to know a priori what is worth re-reading, there are things to be learned from lesser books as well.
1. C.S. Lewis, The Collected Letters of C.S. Lewis: Vol. II: Letter to Arthur Greeves Feb 1932, p. 53.
2. Ibid., p. 54