Alchemists believed human life could grow in horse manure

Centuries before the birth of modern genetics, the leading theory of reproduction held that a father's sperm contained the entire essence of a human being. In this view, the womb was merely a warm vessel for growth, a role that medieval alchemists believed could be replicated using artificial means. They sought to create a homunculus, or little man, by providing the right environmental conditions outside the human body.