What are the most “successful” people in the world reading? The very books that made them rich.

“My wife calls me the Imelda Marcos of books,” Mr. Moritz said in an interview. “As soon as a book enters our home it is guaranteed a permanent place in our lives. Because I have never been able to part with even one, they have gradually accumulated like sediment.”

Serious leaders who are serious readers build personal libraries dedicated to how to think, not how to compete. Ken Lopez, a bookseller in Hadley, Mass., says it is impossible to put together a serious library on almost any subject for less than several hundred thousand dollars.

Perhaps that is why — more than their sex lives or bank accounts — chief executives keep their libraries private.

The most telling thing about this article is the photo that includes that infamous Goethe…