Retired four-star Navy Admiral James Stavridis has 4,000 books in his home library. On one side of his business card his title reads: Dean, Fletcher School of Law and Diplomacy, Tufts University. On the other side, his favorite quote by Thomas Jefferson: “I cannot live without books.”

Stavridis spent more than 37 years in active service in the U.S. Navy, commanding destroyers and a carrier strike group in combat. He spent four years as the Allied Supreme Commander at NATO and has written books that are required reading at the U.S. Naval Academy. His love of books runs deep.

I caught up with Stavridis to talk about his new book, The Leader’s Bookshelf. “A personal bookshelf is critical to developing the ability to inspire others in the pursuit of worthy goals,” he says.

Stavridis makes the compelling argument that military leaders face many of the same challenges as leaders in business, government, academia, medicine, law and sciences: “Creating effective strategies, inspiring subordinates, communicating effectively, building collaborative teams, and developing innovative solutions to seemingly intractable problems.”

In our conversation, Stavridis offered three reasons why books help leaders become more effective, clear and inspiring communicators.

1. There are very few problems that are new challenges

“Almost always you can reach back in history (fiction, memoirs, biographies) and find a problem that is similar to the problem you face today,” says Stavridis.

As Stavridis prepared to take command of a Navy destroyer twenty years ago, he read the 20 classic sea of novels of Patrick O’Brian. By following captain Jack Aubrey in Master and Commander, Stavridis challenged himself and asked, What would I do in that situation?

Throughout history, leaders have used books to train for challenges. Caesar traveled with a library of scrolls. Napoleon brought boxes of books to battle. Admiral Chester Nimitz read classic sea stories during World War II, and the current U.S. Secretary of Defense, General James Mattis, is known for having one of the largest libraries of any military figure in modern history, says Stavridis.

2. Reading enhances a leader’s ability to create powerful, emotional rhetoric to galvanize a team

“The heart of any leader’s suite of tools is communication.” The one book that’s always on Stavridis’ desk is an anthology of great speeches. “When I’m locked up on a communication idea, I’ll read an oration by Socrates, Churchill, FDR, or John F. Kennedy. Reading those speeches will unlock your own rhetoric. Leadership is creating an idea and convincing others that it matters and that it will solve a challenge. To do that you have to communicate the challenge, why it matters and a coherent way to address it.”

3. Reading good, crisp, well-written prose makes you a better writer

“Over time, I became a reasonably good writer because I was an inveterate reader as a child,” says Stavridis. “It’s very hard to teach someone to write, but by reading you become a better writer. Good leaders must be good communicators, and hard work of writing is best sharpened on the whetstone of reading.”

When I told Stavridis that I juggle two or three books a week—non-fiction, history, economics and biographies— he challenged me to read more fiction. Novels, he says, act as a “complex simulator” necessary for successful leadership. “Fiction is a simulator where you can imagine yourself in the challenge that the protagonist faces and you begin to imagine yourself in that situation,” says Stavridis.

Stavridis says novels allow him to learn, grow and develop as a leader, even at the age of 62. “When we stop to learn, we stop to live.” Stavridis believes some leaders do have natural gifts from birth, but great leaders are made. They practice to lead. “The single best way a leader can learn and grow is through reading.”