Where the Sidewalk Ends

During my walks home after elementary school, when I wasn't avoiding the cracks of the grey sidewalk, I would do what you could call a meditation where I would close my eyes and imagine re-opening them to find myself a grown adult. And there are times now when I practice the second half of that meditation, opening my eyes to see I am in fact in the new present, twenty years later. Time is a ruthless arrow. I. Throughout my 20s, my brain (and yours, too) wrapped long-range neural tracks in a fatty substance called myelin (called myelinogenesis), which finishes its optimization loop right around the age I am now. My hippocampus and cortex store a chronological narrative of my life, and at the cellular level, my neurons, telomeres, and metabolic functions accumulate steady wear-and-tear which my internal physiological sensors register as mid-life. My brain cannot keep track of time like a clock or calendar, though. Yesterday and two decades ago sometimes bleed into each other like…