Watching your children grow up is an exercise in the acceptance of mystery.
When your kids are little, you know everything about them. Babies don't keep secrets. Toddlers don't harbor interior lives. But slowly and then quickly, children turn into teenagers, and teenagers are strangers even to themselves. The babies whose hair you can still smell when you close your eyes become their own private universes, both self-contained and limitless.
My boys are 17 and 15, which means I don't know much of anything anymore, especially about them.
Charley, my oldest, has autism, and so he always has stood some version of apart, his true feelings obscured by his scripting and passion for books and trains.