A Supposedly Fun Thing I'll Never Do Again: Essays and Arguments by David Foster Wallace:
I submit that tennis is the most beautiful sport there is, and also the most demanding. It requires body control, hand-eye coordination, quickness, flat-out speed, endurance, and that strange mix of caution and abandon we call courage. It also requires smarts. Just one single shot in one exchange in one point of a high-level match is a nightmare of mechanical variables. Given a net that’s three feet high (at the center) and two players in (unrealistically) a fixed position, the efficacy of one single shot is determined by its angle, depth, pace, and spin. And each of these determinants is itself determined by still other variables—for example, a shot’s depth is determined by the height at which the ball passes over the net combined with some integrated function of pace and spin, with the ball’s height over the net itself determined by the player’s body position, grip on the racquet, degree of backswing, angle of racquet face, and the 3-D coordinates through which the racquet face moves during that interval in which the ball is actually on the strings. The tree of variables and determinants branches out, on and on, and then on even farther when the opponent’s own positions and predilections and the ballistic features of the ball he’s sent you to hit are factored in. No CPU yet existent could compute the expansion of variables for even a single exchange—smoke would come out of the mainframe. The sort of thinking involved is the sort that can be done only by a living and highly conscious entity, and then only unconsciously, i.e. by combining talent with repetition to such an extent that the variables are combined and controlled without conscious thought. In other words, serious tennis is a kind of art.