For the last few years — and, I regret to say, only for the past few years — I’ve been keeping a record of the books I read, and I append a little “r” to the title if it’s one that I’ve read before. But lately I’ve begun to think that I need more categories. For instance, the other day I read E. C. Bentley’s delightful Trent’s Last Case, which I had read before — more than thirty years ago. I didn't remember anything about it except that the protagonist’s name was Trent. That’s a very different kind of re-reading that the experience I recently described of returning to books and finding them more impressive than I had originally found them to be. So I probably need more symbols: RF = I read this before but had forgotten it RU = I read this before but had underrated it RO = I read this before but had overrated it R? = Why in the world did I decide to read this again? Further suggestions welcome.