Here's a video that works in pieces of an interview from 1974 with Muhammad Ali and David Frost, and also gets Ali's thoughts much later in life on that same interview, which was pretty controversial to be sure.

The things Muhammad Ali was saying and doing in 1974 -- it's so hard for me to really gauge or really understand how truly controversial this was, because this had real impact. I'm not trying to make light of the bad or inappropriate things athletes or celebrities might say now, but Ali had true convictions and really believed what he was doing was right. Add in his overwhelmingly powerful personality and the massive chip on his shoulder, plus the fact that he was obviously a professional fighter, and Ali had a serious air of danger about him. He was really fearless.

Modern day Ali is sad to watch. I try not to "feel sorry for him," because he's said many times he doesn't feel sorry for himself, and doesn't want others to feel sorry for him, but it just feels like we were robbed of something more with Ali in his later years.