The vanishing link between animalcules and disease before the 19th century

When Antoni van Leeuwenhoek began his work with microscopes in the late 17th century, western medicine was mostly based on the work of a Roman doctor called Galen (129-199 ad), theological interpretation, superstition, and folk remedies. During modern discussions of Van Leeuwenhoek's work, a common question from listeners is why it took so...