In the late nineteenth century, Louis Pasteur and Antoine Bernard Bechamp were both studying the cause of disease. From their body of work, two schools of thought about disease emerged. Pasteur believed that microbes caused disease, and his work resulted in the germ theory. The germ theory is the basis for modern medicine, killing the germ with a variety of expensive chemical concoctions that must be highly regulated because they are, for the most part, poisons.