The point about all this, though, is that when I was thinking about the book a few days ago, I realized that I couldn't remember a single thing about it. There was all this fascinating biology that I learned from it, except that I clearly didn't learn a thing at all: none of the details stuck. This is not meant as a backhanded criticism of the book. Not at all. In contrast to the content, I recall the sheer thrill of the book extremely clearly. That sense of my world simultaneously expanding and filling up with new wonders, the unique pleasure of previously small mildly curious topics bursting open into impossibly huge flowers of ideas. After childhood, that is a rare experience indeed.
Last night my son wanted me to tell him a story at bath-time and I decided to try my hand at explaining last week's big cosmology discovery. (This is not as outrageous a challenge as it might seem, compared to the more usual requests to concoct an impromptu adventure that includes Horrid Henry, Batman, and Scooby Doo.) We didn't get quite as far as the mechanism behind B-mode polarization of the cosmic microwave background due to primordial gravitational waves; there was a slight misunderstanding earlier on about the basics of the Big Bang. "And that's how the Big Bang made the world?" he asked. "It made the whole universe," I said. His eyes went wide. "The whole universe? Wow!" That was a "wow!" more astounded, more pure, more completely blown away than I have ever had the urge to express in my entire adult scientific career. "Wow!"s like that can spontaneously burst from children ten or twenty times in a single day. And I'm not just talking up my own offspring; all kids do that, even the stupid ones. By contrast that subdued adult joy when your world unexpectedly expands (with or without inflation) is an infrequent experience, and one that's difficult to forget.
Except that apparently it is all too easy to forget. I pulled The Ancestor's Tale off the shelf last night and glanced through it. I vaguely recognized the diagrams at the beginning of each chapter, illustrating where the last chapter's group of species meet their common ancestor in this chapter. But all of the facts, all of the ideas that were so incredible at the time of reading, they were all gone. So what was the point of reading it? This is not the same as asking what was the point of any of the pleasures in life, because the reading was not done simply for pleasure. There are drugs I can take if all I want to do is temporarily fire off a few neurons. The real pleasure comes in the permanent addition to my life; it's like spending a fortune to add an extension to your house, only to have it collapse a week later. And it's different to asking, "What is the point of life itself, since all of the lovely memories we store up in our lifetime disintegrate when we die?" We hope that at least in the time we have, we can learn some interesting things, which we can spend the rest of the time marvelling in and mulling over. But why learn anything if it's going to be gone a month later?
The cure for this quasi-metaphysical downer is quite simple. Learning requires repetition. If I read a book and find it interesting, I don't have to worry about remembering the contents: I just have to remember to read it again. Isn't that a waste of time? Couldn't I be reading something else instead? Sure, but then it's two books that get forgotten in a month, not just one.
There's a perfect related example that comes to mind. A couple of posts back I alluded to Conrad's Heart of Darkness. I can be sure that if I had read that book only once, I would have forgotten it completely. I have also read Conrad's Nostromo, and I don't remember a thing about it, except that there was, perhaps, a mine involved. I read Conrad's Lord Jim, too, and I'm not even sure if I finished it. But Heart of Darkness was different, because after I read it I watched Francis Ford Coppola's incomparable modern cinematic retelling, Apocalypse Now. A few years later some friends decided one evening to watch a double feature of Apocalypse Now and then the unique making-of documentary Hearts of Darkness, which Coppola's wife constructed from footage and recordings she'd taken during the production, some without her husband's permission. I've no idea if their marriage survived this exposé, but I'm hoping that he recognised that her achievement was at least as great as his own. The documentary is packed with astounding moments amid a backdrop of filmmaking chaos. And how do I remember this? Well, compared to some complicated biological phenomenon in The Ancestor's Tale, it's much easier to remember the anguished voice of Coppola after his wife tries to convince him that his film is just like a school essay that he hoped to get an A for, and instead he gets a B, and he cries out, "I'm going to get an F! This is an F!" On the other hand, I've also watched the documentary twice. Somewhere in there I also re-read the book and re-watched the movie. So it's not especially surprising if I remember all three extremely well.
Great, now that's all worked out. The only remaining problem is finding the time to do all this reading. The main text of The Ancestor's Tale is 614 pages. At my current rate I can manage about two pages per week, so it will take six years. That's fine -- it will be time well spent. Assuming the book is as good as I remember it.