In the bustling, sun-baked streets of Miletus, where merchants argued over grain prices and sailors cursed the shifting winds, there lived a man who tried to think past the edge of the visible world. To most people in that Ionian city, the horizon at sea was a simple line: beyond it lay other ports, other gods, other dangers. For Anaximander of Miletus, that hazy band between water and sky was something more. It was an invitation to imagine a structure larger than anything the senses could directly show. Where others saw the earth as resting on something—water, pillars, the back of some creature—Anaximander dared to ask, what if it rests on nothing at all?

He lived in the sixth century BCE, a younger contemporary and likely associate of Thales, who is often called the first philosopher. If Thales was the one who said, “all is water,” Anaxim ...