Somebody recently asked me what I would do if I had $500 million to give away. My first thought was that I’d become a moderate version of the Koch brothers. I’d pay for independent candidates to run against Democratic or Republican members of Congress who veered too far into their party’s fever swamps.

But then I realized that if I really had that money, I’d want to affect a smaller number of people in a more personal and profound way. T he big, est ablished char ities are already fighting disease and poverty as best they can, so in search of new directions I thought, oddly, of friendship.

Ancient writers from Aristotle to Cicero to Montaigne described friendship as the pre-eminent human institution. You can go without marriage, or justice, or honor. but friendship is indispensable to life. Each friendship, they continued, has positive social effects. Lovers face each other, but friends stand side-by-side, facing the world— often working on its behalf. Aristotle suggested that friendship is the cornerstone of society. Montaigne thought that it spreads universal warmth.

These writers probably romanticized friendship. One senses that they did n’t know how to have real conversations with the women in their lives, so they poured their whole emotional lives into male friendships. But I do think they were right in pointing out that friendship is a personal relationship that has radiating social and political benefits.

In the first place, friendship helps people make better judgments. So much of deep friendship is thinking through problems together: what job to take; whom to marry. Friendship allows you to see your own life but with a second sympathetic self.

Second, friends usually bring out better versions of each other. People feel unguarded and fluid with their close friends. If you’re hanging around with a friend, smarter and funnier thoughts tend to come burbling out.

Finally, people behave better if they know their f r iends are obser ving. Fr iendship is based, in part, on common tastes and interests, but it is also based on mutual admiration and reciprocity. People tend to want to live up to their f riends’ high regard. People don’t have close friendships in any hope of selfish gain, but simply for the pleasure itself of feeling known and respected.

It’s also true that friendship is not in great shape in America today. In 1985, people tended to have about th ree really close friends, according to the General Social Survey. By 2004, according to research done at Duke University and the University of Arizona, they were reporting they had only two close conf idants. The number of people who say they have no close confidants at all has tripled over that time.

People seem to have a harder time building friendships across class lines. As societ y becomes more unequal and segmented, invitations come to people on the basis of their job status. Middle-aged people have particular problems nurturing friendships and building new ones. They are so busy with work and kids that friendship gets squeezed out.

So, in the fantasy world in which I have $500 million, I’d try to set up places that would cultivate friendships. I know a lot of people who have been involved in fellowship programs. They m ade friends that ended up utterly transforming their lives. I’d try to take those sorts of networking programs and make them less career oriented and more profound.

To do that, you have to get people out of their normal hunting grounds where their guard is up. You also probably want to give them challenging activities to do together. Nothing inspires friendship like self lessness and cooperation in moments of difficulty. You also want to give them moments when they can share confidences, about big ideas and small worries.

So I envision a string of adult camps or retreat centers (my oldest friendships were formed at summer camp, so I think in those terms). Groups of 20 or 30 would be brought together from all social and demographic groups , and secluded for two week s. They’d prepare and clean up all their meals together, and eating the meals would go on for a while. In the morning, they would read about and discuss big topics. In the afternoons, they’d play sports, take hikes and build something complicated together. At night, there’d be a bar and music.

You couldn’t build a close friendship in that time , but you could plant the seeds for one. As with good fellowship programs, alumni networks would grow spontaneously over time.

People these days are flocking to conferences, ideas festivals and cruises that are really about building friendships, even if they don’t admit it explicitly. The goal of these intensity retreats would be to spark bonds between disparate individuals who, in the outside world, would be completely unlikely to know each other. The benefits of that social bridging, while unplannable, would ripple out in ways long and far- reaching.