"The man who views the world at 50 the same as he did at 20 has wasted 30 years of his life." -Muhammad Ali
Widely regarded as one of the most important figures in all of sports, Ali wrote his autobiography, The Soul of a Butterfly, in 2004. "Over the years my religion has changed and my spirituality has evolved," Ali wrote in the introduction. "My soul has grown over the years, and some of my views have changed. As long as I am alive, I will continue to try to understand more because the work of the heart is never done... I set out on a journey of love, seeking truth, peace and understanding. I am still learning."