bill and melinda gates that were friends for years became a force for good when bilodeau nated back tohe gates foundation. >> it was pretty phenomenal that right as we learned a lot of things and we were building up our capacity that we got this doubling of capacity for things like aggravated assault, things like me lair ya eradication overtime, and we were able to be unbelievably ambitious. in what we're going to do, and that is our life's work now. >> how would you say your friendship and partnership evolved overtime. >> with me it started on july 5th, 1991. bill was reluctantly agrees to meet me, and we hit it off, we started doing things together, one of the great ones was a 17-day trip through china. >> i tease bill because they're came a point in our life that omaha was always on the way to or from the east coast. >> another initiative that you three are actively involved with is the giving pledge, and i know that has been a place where people actively involved in philanthropy can get together and talk about what has and hasn't worked. can you tell us something that comes from th