There’s a certain liquid but frictioned struggle when I walk through the grass in the morning after it rains. My feet, less sure now, more prone to missteps and the cruelty of unbalancing, skim through the green sea of clover and vetch, leaving long strokes like ski tracks behind me. But I do not turn to look at these tracks as I walk, because I do not trust my own footfalls. This, then,  is what aging is: a gradual mistrust of all the powers and agile techniques and reflexive movements that I once took for granted, like a good Catholic who, when he sees death’s cowled head bobbing up over…