It's in this essay that you'll find what might be Wallace's most famous sentence, "I submit that tennis is the most beautiful sport there is, and also the most demanding."
The fourth essay "Democracy and Commerce at the U.S. Open" is a no holds barred take of what it's like to be a spectator at Flushing Meadows in 1995. He dissects food court prices, ticket scams, sponsorships signs and the players themselves (he really unpacks his hatred of Andre Agassi). He describes the American as "scrawny and faggy, and with his shaved skulls and beretish hat and black shoes and socks and patchy goatee, like somebody just released from reform school..."
The fifth and final essay is passionately focused on Roger Federer, and is the most famous of the five. "Federer Both Flesh and Not" introduces something called "Federer Moments" which any tennis fan has witnessed, most likely on TV but if they're lucky, live.
All in all, String Theory is a must-read for anyone that's remotely interested in tennis. Beautifully written and boldly unfiltered, Wallace digs into and exposes the delicate nerve endings on some of the most sensitive topics in the sport.
Wallace wrote a number of other influential books including Infinite Jest, A Supposedly Fun Thing I'll Never Do Again, Brief Interviews with Hideous Men, The Pale King, The Broom of the System, and more. A longtime sufferer of depression, he committed suicide in 2008 at the age of 46.