"But you never know when the magic will descend on you. You never know when the grooves will open up. And once the magic descends you don’t want to change even the smallest detail. You don’t know what concordance of factors and variables yields that calibrated can’t-miss feeling, and you don’t want to soil the magic by trying to figure it out, but you don’t want to change your grip, your stick, your side of the court, your angle of incidence to the sun."