Guest post by Jonathan Eig

Four years ago, a writer friend called for advice. She was trying to decide whether to write a book about Babe Ruth. I quoted Herman Melville to her: “To produce a mighty book, you must choose a mighty theme.” Babe Ruth definitely counted as a mighty theme. Other than Muhammad Ali, I said, no one in the world of sport was mightier than Ruth. I urged her to take on the Babe.

When I hung up the phone, it hit me: Muhammad Ali…that was the mightiest subject of all. I knew immediately that it was the best book idea I’d ever had and probably the best I ever would have. A quick Google search revealed, shockingly, that there had never been a complete, unauthorized biography of the legendary boxing champ and rebel.

For me, a child of the 1970s, there could be nothing more thrilling than writing about Ali. I had his poster on the ceiling of my room when I was a kid. Ali was the most famous and, at least in my mind, the most fascinating man of the 20th century. His story was about race and religion as much as boxing. It had sex and violence. It had Don King and Howard Cosell. How could I go wrong?

Once I started my research, I didn’t want to stop. I told my editor I wanted to spend 25 years writing the book because I was having so much fun. I had to settle for four years. Now it’s done, with publication set for October and a PBS documentary collaboration with Ken Burns in the works.

I had such a blast I decided to create a podcast to tell some of the stories that didn’t make it into the book. It’s called Chasing Ali. We’re releasing it tomorrow for the first anniversary of Ali’s death. You can get it here.

The podcast contains lessons I definitely didn’t get at Medill. For example: What do you do when one of your key sources says she absolutely won’t talk to you unless you pay $6,500? What do you do when you’re hearing three different version of a story from three different people, all of whom were married to your subject? Is it a transgression of journalistic ethics to take your young daughters to Don King’s Christmas party, or is it merely bad parenting?

One of my first interviews was with Dick Gregory, the comedian and civil rights activist, a man who knew Ali well. Gregory warned me I was taking on a nearly impossible task: “It’s almost like trying to tell a story about God,” he said to me. “You can’t.”

I understood his meaning. Ali’s life was big. It was complicated. And I wasn’t there. How was I supposed to know what really motivated him, what really shaped him?

All I could do was try. I did the same thing I’ve been doing for 30 years as a journalist: leg work. I conducted more than 600 interviews, winning the cooperation of almost all of Ali’s close friends and relatives. I filed FOIA requests for FBI documents. I crawled under the bed of Ali’s ex-wife to retrieve a box of old letters, including one explaining why he became a Muslim.

For most of the time I worked on the book, Ali was still alive. Obviously, I wanted to talk to him, too. His wife, Lonnie, suggested that I come to their house and read the book to him when it was finished. Unfortunately, Ali died before I could do that.

But I did make it to Ali’s house and I did get to meet the man who occupied so much of my thought these past four years. You can see the picture of me with Lonnie Ali here. But if you want to know why I’m holding a pink stuffed bunny named Sophie and if you want to know what I said to Ali when I finally met him, you’ll have to listen to the podcast.

For now, I’ll just say this: Melville was right. To produce a mighty book, you must choose a mighty theme. And sometimes you must bring along a pink stuffed bunny named Sophie.

Jonathan Eig is a New York Times best-selling author and a 1986 Medill graduate.