I’ve reread two books this summer, and I’m in the process of rereading a third. In the past, I’ve been unjustifiably resistant to rereading. I figured it was wasteful to spend precious time reading books I’d already read when there were so many out there that I hadn’t. But now I’ve reconsidered. I here offer a list of reasons to reread:
1. Differing rates of diminishing marginal utility. Sure, the marginal utility of a given book may decline with each reading, but it doesn’t always drop to zero after the first. Truly excellent books’ marginal utility starts high and declines slowly. Thus, the marginal utility of rereading an old book can exceed the marginal utility of reading a new one for the first time.
2. Potential for increasing marginal utility. Some books make more sense the second time around. Themes fully developed in the later chapters now jump out more readily in the early chapters. Foreshadowing you blew past the first time, because you didn’t know what was to come, now becomes apparent.
3. Complementarity with subsequent reading and education. Your understanding and appreciation of a book depends, in large part, on what you bring to the table. Lacking the optimal background and stock of knowledge, you might fail to appreciate the best material. Go back when you’ve learned a bit more, and you’ll find insights that resonate more than they did the first time around.
4. Known quantities versus expected values. You know what quality to expect from a book you’ve read before. By contrast, any new book is a gamble. It could be great, or it could be lousy. This lowers the expected value of new reading relative to rereading.
5. Forgetfulness. An obvious point, but still true. Wait long enough, and rereading a book is almost like reading it for the first time again. (However, forgetfulness can also diminish the "known quantities" point above. The first of this summer's rereads was not nearly as good as I'd remembered, for example. That is one of the dangers of rereading, but it's no greater than the danger of a new read. The other two have been at least as good as I remembered.)
A solicitation for comments: What books have you reread most often? And what characteristics are common to the most rereadable books?