There he sits, unnoticed, at the edge of Central Park: a flop of hair across his forehead, chin up, eyes blazing. He doesn’t have a body, just a torso resting on a pedestal that says, in simple, bold block letters: HUMBOLDT. No first name, like he’s that famous.

Humboldt? Humboldt who? About 150 years ago, that was like asking Madonna who? Or Beyonce who? Or Napoleon who? Everybody knew. He was spectacularly famous.

On September 14, 1869, though he’d been dead for ten years, all over the world people celebrated his 100th birthday: In Alexandria, Egypt, there was a fireworks display. Crowds gathered in Melbourne, Adelaide, Moscow, and Mexico City. In Berlin, the day was declared a local holiday and—in the