Spontaneous generation

Spontaneous generation, or abiogenesis, theory that living creatures can arise from nonliving matter. Dating from the writings of Aristotle, the idea remained current even after it had become clear that higher orders of life could not be created in this way. It was only with the work of Francesco Redi (1626–97), showing that maggots did not appear in decaying meat protected from flies, and Louis Pasteur (1822–95), who proved that the equivalent was true of microorganisms (i.e., bacteria), that the theory was finally discarded.