The first person to propose the theory of spontaneous generation, that life arose from non-life, was Anaximander, a Greek philosopher who lived between 610 to 546 B.C. This idea was propagated by Aristotle, and through Aristotle's writings, this theory was promoted by the Catholic Church.
Medieval Europeans believed that animals such as mice could be spontaneously created by leaving fouled clothing out and waiting a certain period of time. While mice would probably be attracted to the fouled clothing, it is impossible to create such complicated creatures using only patience and dirty laundry. The theory of spontaneous generation was not thoroughly debunked until the experiments of Louis Pasteur in the 1860s.