When Muhammad Ali became the world heavyweight champion in 1964, he was not the first African American boxer to hold the title. Ali took it upon himself, however, to show that he was different, in his words, “a new kind of black man.” As a powerful athlete who moved like a dancer and spoke like a poet, he was resolutely unique.

David Remnick’s biography picks up Ali’s life when he was still known as Cassius Clay, his birth name. Clay rose to international prominence by winning gold in the 1960 Olympics, and then set about working his way through all the top boxers, generally winning but also generating controversy. The book covers his two fights with Sonny Liston, taking the world title in 1964 when he was only 22, and again in 1965. It also discusses his two fights with the former champion, Floyd Patterson, which reaffirmed his dominance and unquenchable ego.

Ali made a major contribution to American culture, Remnick shows throughout the book, and did so only partly in the boxing world. His powerful personality and refusal to show false modesty made him a lightning rod for American attitudes toward African Americans. Ali’s contribution was as much to civil rights as to sports.

The importance of religion for African Americans, especially the ascent of the Muslim faith, is another significant theme. While still Cassius Clay, he had converted to Islam and was close to Elijah Muhammad, the controversial leader of the Nation of Islam. Ali’s decision both to change his name and to publicly discuss his faith—after boxing promoters had encouraged him to reject it—were significant milestones for a sports figure to espouse a controversial position.

The principles of taking a political stand, especially through Ali’s opposition to the Vietnam War, are another theme. When Ali was drafted and registered as a conscientious objector, he was the highest-profile man yet to have done so. Resisting all pressure to change his position, even the threat of jail, Ali’s courage inspired others who spoke out for defending one’s principles. In pointing out that African Americans faced hostilities at home every day, and that Vietnamese people had never insulted him, he gave voice to thoughts that many were reluctant to discuss.