How Science Lost God

In the seventeenth century, most natural philosophers believed that every type of living organism on the face of the Earth had always existed, from the very beginning of the Earth’s creation. Every organism—every dog, every bird, every human being, and every worm—had been created by God in the form of something called “germs.” These germs were like the seeds of plants, scattered at the dawn of creation by God over the face of the planet, like a gardener would scatter a future crop. Germs were tiny, far too small to be seen even with the aid of a microscope. And each such germ contained even tinier germs, the germs of every successive generation that any creature would ever spawn. They were all stacked inside each other, like Russian nesting dolls. The infinite nature of the theory was the one thing that people had a hard time coming to grips with, but one of the theory’s most influential proponents, the French philosopher Nicolas Malebranche, would point out that it was no harder to believe in germs than in the life cycles of plants.* “One can say that in a single apple pit,” he said, “there would be apple trees, apples, and the seeds of apples for infinite or almost infinite centuries.”