It seems that being a billionaire doesn’t necessarily overshadow one’s humility. Ray Dalio runs Bridgewater Associates, the world’s biggest hedge fund, which he started in a two-bedroom apartment 40 years ago. According to a Forbe’s estimate, Dalio is worth around $15.6 billion, and his fund employs 1,500 people and manages about $150 billion in assets.

In an interview with psychology professor Robert Kegan of Harvard University, however, the investment behemoth discussed how making mistakes and disagreement is part of his process. “Can we be straight with each other? Can we work it through? That’s the essence of it,” Dalio explains. He has written down his ideas in something called “The Principles”, which is available on the Bridgewater website (and has been downloaded 2 million times). He says, “In order to be successful in markets…you need to have a view that’s different from others…but there’s a high probability that you’re wrong, so you need to thrash it out.”

On being a “Professional Mistake Maker”, Dalio quips, “I’m lucky two-thirds of my trades are right.” He shares that it has been helpful to write down mistakes so that he could recall what his criteria were for making them. He says, “Success comes from knowing what you don’t know more than what you do know.” His centered approach to work and life may come from the fact that he has practiced transcendental meditation since 1969. “It gives you equanimity. It means a lot to me,” he says.

So, apparently, does giving back. Dalio signed the Bill Gates and Warren Buffett-backed Giving Pledge, a promise to give away at least half of his wealth to charity. “I don’t think giving my kids a lot of money is a good idea,” he says. “The best thing I could give them is strength. Struggling gives you strength.”