What inspires Bill Gates?

What inspires a billionaire? In the case of Bill Gates, it's a 500-year-old manuscript penned by Italian genius Leonardo da Vinci. And at $30.8 million, it was probably a bargain to the Microsoft founder, who considers it a priceless symbol of knowledge. Charlie Rose talks to Gates about the historic document -- the world's most valuable -- for a 60 Minutes story to be broadcast Sunday, May 12 at 7 p.m. ET/PT.

Gates won't entertain comparisons of his life to that of da Vinci, who conceived of airplanes and helicopters hundreds of years before they were built, but says the great thinker was way ahead of his time. "He had an understanding of science that was more advanced than anybody else at the time," says Gates, referring to da Vinci's writings about water displayed in his private office in Seattle. "He's looking at how it flows when it hits barriers and it goes around and comes back together. He's actually trying to understand turbulence. How you build a dam, does it erode away?"

What makes the ancient text so priceless to Gates is what it stands for: a quest for knowledge he embraces completely and that continues to inspire him. "It's an inspiration, that one person off on their own with no positive feedback...that he kept pushing himself...found knowledge in itself to be a beautiful thing," Gates tells Rose.

Da Vinci's ideas were futuristic. Gates' may be realized much sooner. He shows Rose prototypes of inventions now being worked on that will help change the world for many, especially the world's poorest people.

Gates has invested in a nuclear reactor that would burn depleted uranium. He predicts the reactor, which is cheaper, cleaner and safer than those of today, could be built in a decade or less. But another invention, a thermos system that can keep vaccines cold and potent for 50 days, will soon be deployed to help eradicate preventable diseases.