Toothache has been the most ubiquitous ailment to plague mankind from time immemorial. Until the late 1700s, it was thought that the cause of this torment was the wriggling, in a carious tooth, of a worm. And early attempts at treatment were focused on driving the "worm" out. It was one of the world's greatest scientists, the dentist W. D. Miller, who, after extensive research, in 1891 published his epochal work, The Microorganisms of the Human Mouth, which set forth a new theory regarding the cause of dental caries. His postulating a "chemico-parasitic" origin of caries laid the basis for all the modern research in dentistry aimed at wiping this scourge out. Contemporary research has proven the worth of Miller's groundbreaking theory.