I can't tell you how I know. So don't believe me.
I've sat beside an old woman, wrapped rapidly in her scent of knitting and glandular perfume, whispering. I've done the correct things, things I read in books, some ceremony I only understand while I'm doing it. I've felt the sense in the quiet, listening for a gift. Received the gift and been awed by it. Watched it evaporate like a lens flare.
Thought in microseconds. I couldn't say where, but I know that heartrate. Look around and you see your limbs in poetry that will determine whether you remember as muddled survivor or tragedy. They used to say in karate class, "no wasted motion". Indeed, you're not even coming up with the motion, let alone overthinking or wasting it. It's slick like clockwork and you're down on the pavement, the texture of wet gravel burned into your cheek, and you're safe as houses.
And power. Testosterone like the sulfur flare of a firecracker in the air and a stranger's small flesh suddenly against you. You realize you're muscle under there. Your arms are smaller than hers, but you're taller, you wrap her up and protect her. The fight breaks up and she says, "oh", and blushes.
Am I losing my mind? Because I'm too early to lose my memory. Am I inventing events or are events rolling over me and leaving just the footprints of the feeling?
The end, when the ocean washes up to take us home. The grey horizon where the clouds blend into the air and the sea in the same stoic color. The last salty breath when you know who you were. Know what we're meant to return to. That's the most fantastic of all, and I know when that one happened.
It must be delusion. Watch out, now. You get old and you look down to find your life is just the mascara on your pillow.