The Theory of Spontaneous Generation

Yet, this is modern-day common sense. Common sense in other times told people quite a different thing. They saw earthworms arising from the mud, especially after a rain. They saw maggots coming out of the garbage. They saw evidence all around them of life arising from nonliving precursors-of the spontaneous generation of life. In fact, Jan van Helmont (1577-1644) passed on a recipe for making mice:put some old rags in a dark comer, sprinkle some grains of wheat on the rags, and in twenty-one days you have mice. The mice presumably generated spontaneously.

Francesco Redi (1626-1697) was the first to investigate the theory of spontaneous generation of life. He took two dishes of meat, covered one with gauze, left the other dish uncovered, and let both dishes stand for a time. While the meat in both dishes decayed, only the uncovered dish developed maggots. Redi’s experiment did not disprove the spontaneous generation of life, however; it disproved only the spontaneous generation of maggots.