Up until 1668 and Francesco Redi's rotting meat experiments, sex and birth were universally misunderstood. Chinese Buddhists believed all things came from germs. Ancient Egyptians believed frogs came from mud. Medieval Europeans believed mice came from mouldy, rotten wheat and rats from sewerage.

Birth was due to spontaneous generation or divine intervention, or so it was thought.

Christian Europe believed it was God who was responsible for children. God blessed and rewarded marriage and the union of men and women with children...God's little gifts. There was absolutely no understanding of the connection between intercourse and the birth nine months later of a child. (Thus some very large families.)

Redi questioned this doctrine of spontaneous generation. His experiments proved meat became infested with maggots when contacted by flies. Therefore the air and the divine had little to do with the creation of living organisms.

The Italian's experiments were simple. Meat was placed inside three jars. One jar was covered with a lid. On another he placed a piece of gauze fabric allowing the flow of air and smells. No cover was placed on the third jar. After a number of days he noticed only the uncovered jar held maggots and rotting meat. And on the gauze covered jar he noticed eggs. He scraped the eggs off the gauze, dropped them onto the clean meat and noticed they turned into maggots and then flies. His simple experiment had shown it was living organisms which created other living organisms and not the air, earth or non-living matter.

Thus thanks to maggots and rotting meat we understand a whole lot more about living organisms and... sex.