On October 4, 1986, the University of Alabama hosted Notre Dame in a game of football. Notre Dame had won the previous four contests, but this time Alabama was favored. It had a stifling defense and a swift senior linebacker named Cornelius Bennett. Ray Perkins, Alabama's head coach, said of him, "I don't think there's a better player in America." Early in the game, with the score tied, Bennett blitzed Notre Dame's quarterback, Steve Beuerlein. "I was like a speeding train, and Beuerlein just happened to be standing on the railroad track," Bennett told me recently. Football is essentially a spectacle of car crashes. In 2004, researchers at the University of North Carolina, examining data gathered from helmet-mounted sensors, discovered that many football collisions compare in intensity to a vehicle smashing into a wall at twenty-five miles per hour. Bennett, who weighed two hundred and thirty-five pounds, drove his shoulder into Beuerlein's chest and heard what sounded like a balloon being punctured--"basically, the air going out of him." Beuerlein landed on his back. He stood up, wobbly and dazed. "I saw mouths moving, but I heard no voices," he later said. After Bennett's "vicious, high-speed direct slam," as the Times put it, Alabama seized the momentum and won, 28–10. Following college, Bennett was drafted into the National Football League. Between 1987 and 1995, he played for the Buffalo Bills, and appeared in four Super Bowls. During his pro career, he made more than a thousand tackles, playing through sprains, muscle tears, broken bones, and concussions. I asked him how many concussions he'd had. "In my medical file, there are probably six." "I couldn't even begin to tell you." "I played a long time," he said. "Every week after a game, I got some sort of headache." In 1996, he signed a thirteen-million-dollar contract with the Atlanta Falcons. He received weekly injections of Toradol, an anti-inflammatory drug. "It was magic--it made me feel like I was twenty-four again," Bennett said. He helped carry Atlanta to the Super Bowl--his fifth. In 2000, at the age of thirty-five, Bennett retired and moved to Florida. He lived in a hotel in Miami's Bal Harbour area, worked on his golf handicap, and vacationed with his wife and friends in Europe and in the Napa Valley. Several of Bennett's football peers were having a far tougher time. Darryl Talley, a former Bills teammate, suffered from severe depression. Mike Webster, a Hall of Fame center for the Pittsburgh Steelers, had become a homeless alcoholic; he died, of a heart attack, in 2002. Three years later, Terry Long, another former Steeler, committed suicide by drinking antifreeze. Andre Waters, a former Philadelphia Eagles safety, killed himself with a gunshot to the head. A neuropathologist named Bennet Omalu autopsied Webster, Long, and Waters, and detected a pattern: each had a high concentration of an abnormal form of a protein, called tau, on his brain.