Neil Leifer first had the good fortune to photograph Muhammad Ali at a 1963 fight in New York City. Both men were just starting their professional lives. Leifer, then just 20 years old, was on assignment for Sports Illustrated; Ali -- then known as Cassius Clay -- was 21 with 17 pro bouts under his belt. Over the next 20 years Leifer documented Ali's brilliant ring career and forged a personal relationship with the champ, continuing to shoot Ali in a series of portraits and sittings for another two decades. "My favorite subject, no matter what the sport, was and still is Muhammad Ali," says Leifer of their more-than-40-year bond, represented by 64 photo sessions.<br> <br>Now on the occasion of his 70th birthday, Ali is celebrated through Leifer's unique archive of images, amassed and annotated to announce, just as the boxer himself used to boast, that Ali is the Greatest of All Time. "Body language says a lot and Muhammad always, always carried himself like a champion," notes the photographer. Widely regarded as the Sportsman of the Century for his actions both between the ropes and off the canvas, Ali is defined through Leifer's lens. In this 96-page collection, Ali's brand of showmanship and hallmark of social activism are never more apparent. Statesman and icon, Ali and his revolutionary existence are honored in Leifer's work.