Two years and one month ago, I was navigating the summit ridge of Mount Everest under a spectacular purple dawn. My Sherpa companion and I had climbed through the night, slowly making our way from Camp 4 into the so-called death zone, and the darkness was beginning to soften. From that elevation, I could see the horizon gently curving against the corners of the sky. 

The summit ridge is narrow — knife-edge narrow, in places — and the consequence of placing my foot a few inches to either side of precision was death. I’d already calculated: if I fell off that summit ridge, I would freefall for more than a minute before impact. Don’t think about that, I told myself. Keep walking. Breathe in, breathe out. I was keyed into every sensation: I felt the crisp snow under each footfall, the frozen saliva down my chin, the icicles in my hair.

It was absolutely, without a doubt, the single hour of my life when I felt both the most acute elation and the most acute fear. Today, when I close my eyes and reach for my center, it’s still that ridge I see.