Recently, a pediatrician friend remarked that people – patients’ parents, friends, strangers she chats with briefly in airports and coffee lines – were always asking her for recommendations on the best books about childhood.

I had to admit that I don’t get many requests about books on old age.

That’s a shame, because there are a lot of them, and some are quite good. But in looking through my growing collection of these books to decide which I might recommend if I were ever asked, I realized tha...