Science, as some believe, is a continuing struggle to disprove existing theories and establish proven facts in their place. Such is the case with Francesco Redi, an Italian physician and naturalist. He was born in 1626, in Tuscany, Italy, where theory, rather than fact, dominated much of the logic used to explain certain happenings in life.
For instance, due to the fact that there were no refrigerating devices during the 1600s, meat often rotted. As a result of the meat rotting, people came to believe that the meat spontaneously generated maggots, organisms that would eat away at the rotting flesh. Redi found this assumed theory of abiogenesis, or the concept of living organisms arising from non-living organisms, rather difficult to believe. He proceeded to thoroughly study and investigate the meat, and the process by which it rotted. The experiment he designed, although innovative and quite brilliant, was rather simple.
Redi decided that a more plausible method of maggots developing would be that they were organisms hatched from eggs laid by flies. He made this his hypothesis, and attempted to prove it. First, he placed four slabs of meat into four separate, open jars, leaving them exposed to the air. He observed flies laying eggs onto the meat, as he predicted. Maggots did in fact hatch from the eggs, and eat away at the meat.
Then, he placed four pieces of meat into four separate jars and sealed them. By sealing them, he ensured that no stench would escape and that it would not be exposed to flies. Because there was no stench, no flies were attracted to the jar and therefore no maggots were produced, thus proving Redi's hypothesis. His hypothesis was that the meat, rather than spontaneously generating maggots, attracts flies who then lay them.