By January, after Mr. Trump’s election, Mr. Belafonte was more focused on the new president, whose coming administration he had compared to a “Fourth Reich.” Mr. Trump, he said, was not a break from America’s traditions but a resurfacing of energies that have been there all along.

“I look at him as a continuation,” he said. “With all of the images that we throw up about our generosity as a nation and so forth, America tends to ignore the fact that there is a parallel history from which we come that’s not quite so pleasant. And I think Donald Trump reminds us that that value, that negative component, is still strongly in our midst.”

Looking ahead, he said, “I often think about how the German right wing emerged in the ’30s and ’40s, and what came of that, and I think we’re in the same space. Here we are, a highly educated, highly economically secure society. Everything is in our favor, and if everything is in our favor, what is it that we want as a people and as a nation that makes Trump so attractive? Something’s askew here, terribly askew.

“I think it’s an opportunity for the left to take this wake-up call. We need to be much more radical in what we do and how we do it than we have been up to now. The liberal community has compromised itself out of existence. The black community has been so passive in its response to this onslaught. Labor is strangely silent. All those reverends that were part of the progressive front are no longer heard from in any appreciative way. And out of that vacuum comes Trump.”

Yet Mr. Belafonte was not mired in despair. In his apartment, he has a hallway of photographs of himself with Dr. King and other important figures from his life, with one wall showing them angry or mournful, and on the other wall smiling or laughing. “I love the happy wall,” he said. “People never get to see that side.”

With his milestone birthday around the corner, he was re-examining moments from his past, counting his fortunes along with his mistakes. New York, he said, still mystified him in its grandness — as unlikely as his own rich life.

“I think there’s no city quite like New York,” he said, “and I’ve seen most of the developed cities of the world. I admire this place, its energy. It’s the repository of so much history and culture and diversity. I think New York City most represents what it is that America in general aspires to. It’s big, it’s dense. I’ve known this city from all of its social arcs. The best that’s in America is yet to come. The worst that’s in America is yet to come.”