IN AMSTERDAM I met a man who revealed to me the hidden currents of our lives—the massive flows of raw materials and products deployed, to such wonderful and damaging effect, by 7.7 billion humans. Our shared metabolism, you might say. It was a crisp fall morning, and I was sitting in a magnificent old brick pile on the Oosterpark, a palace of curved corridors and grand staircases and useless turrets. A century ago, when the Dutch were still extracting coffee, oil, and rubber from their colony in Indonesia, this building had been erected as a colonial research institute. Now it houses assorted do-gooder organizations. The one Marc de Wit works for is called Circle Economy, and it’s part of a buzzing international movement that aims to reform how we’ve done just about everything for the past two centuries—since the rise of the steam engine, “if you need to pinpoint a time,” de Wit said.