The other thing about time passing is that after a few hundred years it gets impossible to find a good catamite. There are alternatives, of course, but any diet suffers for lack of variety: it’s as if apples were going extinct. Longinus finds himself going to preposterous lengths just for an afternoon with a companionable nine-year-old. It’s one such fit of desperation that drives him to learn Japanese, just in time to get expelled by the shogunate.
He tries thinking about it in terms of relative ages, but it’s no use, and anyway mathematics always made him go soft.