When scientists began to take a closer look at the natural world all around them, they did not always agree on what they saw. They did not always accurately understand what they saw. They often jumped to conclusions, especially if they were still influenced by the belief in spontaneous generation. The old, traditional belief that living things could come from non-living things-–still held by many––caused some especially heated debates.

In 1620 Dr. Jan Baptista van Delmont wrote and published a paper to prove that living things DID come from non-living things. Based on what he, personally, had seen, he wrote a recipe for making mice! (Why anyone would want to make mice, I don’t know, I guess he wasn’t concerned with that.)

According to Dr. van Delmont, if you put a piece of sweaty, smelly underwear in an open mouth jar and added some wheat, in twenty-one days full-grown mice would emerge. This was considered scientific observation at that time; not quite the way Maria Sybilla Merian handled her observations of the transformations of caterpillars into butterflies and moths. She studied the caterpillars carefully, documenting with notes and paintings all of the changes that occurred. In fact, she thoroughly documented the entire life cycle…proving that caterpillars did not just ooze up out of the ground, but came from eggs that the butterflies and moths laid. Her method of research is still used today.