“It’s like having a baby,” I found myself saying to Rowan on Saturday, thinking to myself even as the words came out of my mouth that this was a ridiculous metaphor for a six-year-old boy struggling with gravity. But I continued, anyway. “It’s like having a baby and you don’t know exactly when it’s going to happen, or how, but you know it’s going to happen really, really soon. You know?” Of course he doesn’t know, except that his eyes widened, and he nodded. “Yeah,” he said. “It’s going to happen really soon.”

And then, not eleven minutes later, he took both feet off the ground and placed them squarely on the pedals of his two-wheeled bike, stripped a week earlier of training wheels, and cycled the length of our driveway and back, and again, and again, and again. (Which is, come to think of it, pretty much exactly the way his brother came into the world: quickly and easily with almost no build-up, unless you count the preceding nine months or so.)

You’d think I’d be used to these milestones by now, raining down like hailstones — exactly, in fact, like the hailstones that appeared out of nowhere yesterday and covered the lawn with balls of ice the size of giant olives — over the last five months: Rowan swims! Rowan skates! First wiggly tooth! First lost tooth! Ties own shoelaces! Rowan blows his own nose! But no, I don’t get used to them. Watching him pedal furiously by on his bike, balancing on only two tires and sheer will, I thought of the scene in ET when the kids all of a sudden rise into the air on their bikes and fly. In other words, thrilling.

“Does it feel like flying?” I called out to him, and he called back “Yeah!”

And of course, there’s no going back, no (barring tragedy) un-getting your balance. Your whole life is has led up precisely to this point, and then it happens in an instant. In an instant, a paradigm shifts and you are a person who rides upright on two wheels, and how or why on earth would you have ever done anything differently? It is like being born, it is, that first breath drawn and cord clamped and cut and why which you ever breathe anything but air, ever, ever again?