Bill Gates says an essay collection from 1969 is the business book that helped him most in his career

When Bill Gates says a book changed his life, it's worth checking out.

Three years ago, Gates had his favorite business book, 1969's "Business Adventures" by John Brooks, pulled out of obscurity and put back into print. With the force of Gates' passionate recommendation behind it, it became a bestseller.

He continues to publicly vouch for it, most recently on Monday in a Reddit AMA, in response to the question, "Was there any book that helped you through your career?"

On his personal blog, Gates said that he fell in love with the book, a collection of Brooks' New Yorker articles detailing some of the most important events in corporate America in the mid-20th century, back in 1991, when he was still CEO of Microsoft. He had asked Berkshire Hathaway CEO Warren Buffett what his favorite business book was, and Buffett responded by sending Gates his personal copy of "Business Adventures."

"Brooks's work is a great reminder that the rules for running a strong business and creating value haven't changed," Gates wrote in his post.

We've gone through "Business Adventures" and highlighted some of its key lessons that are still applicable today: