Robert Hooke was astonished when he used the higher power magnification and saw the tiny animals swimming in drops of rainwater and bits of spit. The discovery of these tiny monsters changed the understanding of the natural world. With microscopes, scientists could see the tiny eggs that flies laid in meat. Antonie van Leeuwenhoek was inspired by Hooke’s book to create his own set of magnifying lenses to study the “unseen” world. Sounds crazy, but without microscopes, people could not see the tiny eggs laid by invertebrate animals, so they believed the animals were created out of air, meat, or plants. Ancient Greek philosophers like Aristotle and Herodotus firmly believed that tiny animals just magically appeared in flower buds or rotten meat.