David Foster Wallace's 'String Theory' collects his legendary tennis essays, works that transcend sports writing to become meditations on beauty, excellence, and what it means to exist in a body. The centerpiece is 'Federer Both Flesh and Not,' a portrait of Roger Federer in his prime that attempts to capture what watching genius looks like, the 'kinetic beauty' that makes spectators gasp. Wallace, himself a competitive junior player, writes about tennis with technical precision and metaphysical ambition, finding in the sport occasions for thinking about the limits of human capacity. Other essays examine Tracy Austin's disappointing memoir, the peculiar demands of the professional tour, and Wallace's own memories of playing in the juniors, where he learned that his moderate talent would never be enough. The essays showcase Wallace's distinctive style, with their footnotes, digressions, and insistence that apparently trivial subjects deserve serious attention. For Wallace, tennis was never just tennis; it was a laboratory for examining how exceptional ability relates to consciousness, how bodies and minds coordinate in ways that defeat description. Readers who love tennis will find their sport illuminated; those indifferent to it will find writing that makes the game matter.