If you’re going to make your way in the world of the wealthy these days, you’ve got to show you care about the poor. Elite American schools are blooming with philanthropic groups and activities: spend a semester in sub-Saharan Africa; learn how to measure the effectiveness of nonprofits; maximize your impact.

The experience, of course, is “life-changing”: put it on your college application, talk about it over cocktails. It’s the way you become a person of privilege, but also of substance.

This phenomenon has a past worth understanding. The poor have long provided cultural currency to the rich; in previous moments of intense inequality, the social attitudes and political ideology of elites have understood the ghetto as a credibility gold mine. As the echo of the Gilded Age in our own time has grown clearer, the meanings — and failures — of elite progressivism have become more urgent to understand.