If there is one leadership trait that gets listed more than any other it would have to be the willingness to read. Reading is where concentrated and thoughtful learning occurs so it's no wonder the greatest leaders read rather than getting their information from condensed sources like television.

Today great writing can be found in audio form, allowing anyone to dig deep into a subject that will entertain, inform and enlighten. Below are 25 of the greatest leaders and the books they have recommended over the years. This is a must read list for anyone who aspires to greatness.

1. Winston Churchill - by H.G. Wells; "[It is] a wonderful book, in the same class as Gulliver's Travels. It is one of the books I would like to take with me to Purgatory."

2. Albert Einstein - by Miguel de Cervantes, which is the book the scientist most enjoyed for relaxation.

3. Pope Francis - by Robert Hugh Benson; "Reading it you'll understand what I mean by ideological colonization."

4. Martin Luther King, Jr. - by Henry David Thoreau; "During my student days I read Henry David Thoreau's essay On Civil Disobedience for the first time. Here, in this courageous New Englander's refusal to pay his taxes and his choice of jail rather than support a war that would spread slavery's territory into Mexico, I made my first contact with the theory of nonviolent resistance. Fascinated by the idea of refusing to cooperate with an evil system, I was so deeply moved that I reread the work several times."

5. Nelson Mandela - , which circulated among the inmates where he was imprisoned. He signed his name next to his favorite line: "Cowards die many times before their deaths/The valiant never taste of death but once."

6. Angela Merkel - by Goethe; "This works gives you an idea of why we Germans want to get to the bottom of things. It also poses important questions about the responsibility of the scientist."

7. Rosa Parks - by Morris Dee

8. Margaret Thatcher - Adam Smith's

9. Abraham Lincoln -

10. Hillary Clinton - Her favorite book is The Brothers Karamazov by Dostoevsky, but she also highly recommends "[It] shows how most everybody has some conservative and liberal impulses, but just as individuals have to reconcile them within themselves, so does our political system if we expect to function productively."

11. Ernest Hemingway - by Virginia Woolf

12. Fredrick Douglas - by Solomon Northup

13. Steve Jobs - by Clayton M. Christensen

14. George R.R. Martin - Emily St. John Mandel's

15. F. Scott Fitzgerald - , ed. Gardner Murphy

16. J.K. Rowling - by E. Nesbit

17. Stephen King - Lord of the Flies by William Golding

18. Kate Winslet - , Emile Zola

19. George Clooney - , Leo Tolstoy

20. Will Smith - , Paolo Coehlo; "Paulo Coelho in The Alchemist, which is my favorite book, he talks about the whole of the universe, and it's contained in one grain of sand. For years I've been saying that, and now it's really starting to expose itself to me. My own grain of sand has been story. The next 10 years will be my peak of innovation in filmmaking and just as a human being."

21. Natalie Portman - , David Mitchell; "This was the present I gave everyone I knew for three years. It's six different stories told in different time periods and genres: One is historical fiction, another is a '70s thriller mystery, the sixth is a post-apocalyptic story. It's one of the most beautiful, entertaining, challenging books--something that takes all your attention. I think the stories are meditations on violence, specifically the necessity of violence. The book ends with a beautiful exchange: '...only as you gasp your dying breath shall you understand, your life amounted to no more than one drop in a limitless ocean! Yet what is an ocean but a multitude of drops.'"

22. Jay-Z - Homer's and by Malcolm Gladwell;

On The Odyssey: "This epic poem was kind of difficult for me to get through, but it has a beautiful rhythm. I got lost in reading about Odysseus' struggle to get home and his longing for someone so strong, as his wife was, waiting for him. That's like a dream--that kind of strength, love, loyalty."

On Outliers: "This book is about the principles of timing and repetition--about preparing yourself for luck, really. He talks about a hockey team, and how the players born in January had a year up on the guys born in December. They were fortunate that their birthday was early, but they also practiced--they put the work in. The book resonated with me because I was born at a time when there was an influx of incredible music into the culture, and I was lucky that my mom and pop were huge record collectors. In my house, I had music by Michael Jackson, Marvin Gaye, Prince, and the Commodores, and I'm listening to it every single day."

23. Beyonce - by Marianne Schnall

24. Ghandi - Tolstoy's

25. Ellen DeGeneres - by Garth Stein; "I haven't been able to put it down... Your family will love it. You friends will love it. And call me a gambler, but I'd put money on the fact that even your cats will want you to read it to them again and again."