Warren Buffett says these billionaires' letters might be more valuable than their money

Alex Wong/Getty Images

Berkshire Hathaway CEO Warren Buffett participates in a discussion during the White House Summit on the United State Of Women June 14, 2016 in Washington, DC.

Warren Buffett wants his Giving Pledge to define philanthropy for generations.

At the 2016 Concordia Summit in New York on Tuesday, Buffett discussed the philanthropic movement with Yahoo Finance editor Andy Serwer via video conference. The Giving Pledge is a group for billionaires who publicly promise to donate at least half of their wealth to charity during their lifetime or upon death.

Buffett founded it in 2010 with Bill Gates, and the Giving Pledge now has 156 members, many of whom sign along with their spouse, showing that it's a family commitment.

Each member writes a letter explaining why they are making the decision, and Buffett says these are not merely press releases, and may even be more important than any single donation "because they're messages to the future." Buffett explained that they "will be influencing philanthropy 10, 20, 50 years from now, just like Andrew Carnegie's 'Gospel of Wealth.'"

He told Serwer that he is most proud of the younger signatories, like the cofounders of Airbnb. "I tell them, every one of them is worth 10 of me because you're going to have young people, particularly in this day and age, get wealthy very early and they're going to look to the people who are their heroes, whether it's Mark Zuckerberg or Brian Chesky," he said.

We've collected samples from some of the letters below, and all can be read on the Giving Pledge's website.