cranioscopy which involved reading the skull's shape as it pertained to the individual. It was Gall's collaborator Johann Gaspar Spurzheim who would popularize the term "phrenology". In 1809 Gall began writing his principal work, The Anatomy and Physiology of the Nervous System in General, and of the Brain in Particular, with Observations upon the possibility of ascertaining the several Intellectual and Moral Dispositions of Man and Animal, by the configuration of their Heads. It was not published until 1819. In the introduction to this main work, Gall makes the following statement in regard to his doctrinal principles, which comprise the intellectual basis of phrenology: Through careful observation and extensive experimentation, Gall believed he had established a relationship between aspects of character, called faculties, with precise organs in the brain. Johann Spurzheim was Gall's most important collaborator. He worked as Gall's anatomist until 1813 when for unknown reasons they had a permanent falling out. Publishing under his own name Spurzheim successfully disseminated phrenology throughout the United Kingdom during his lecture tours through 1814 and 1815 and the United States in 1832 where he would eventually die. Gall was more concerned with creating a physical science, so it was through Spurzheim that phrenology was first spread throughout Europe and America. Phrenology, while not universally accepted, was hardly a fringe phenomenon of the era. George Combe would become the chief promoter of phrenology throughout the English-speaking world after he viewed a brain dissection by Spurzheim, convincing him of phrenology's merits. The popularization of phrenology in the middle and working classes was due in part to the idea that scientific knowledge was important and an indication of sophistication and modernity. Cheap and plentiful pamphlets, as well as the growing popularity of scientific lectures as entertainment, also helped spread phrenology to the masses. Combe created a system of philosophy of the human mind that became popular with the masses because of its simplified principles and wide range of social applications that were in harmony with the liberal Victorian world view. George Combe's book On the Constitution of Man and its Relationship to External Objects sold over 200,000 copies through nine editions. Combe also devoted a large portion of his book to reconciling religion and phrenology, which had long been a sticking point. Another reason for its popularity was that phrenology balanced between free will and determinism. A person's inherent faculties were clear, and no faculty