The first way that Paracelsian medicine changed the sale of medicines was because it was an alternative to Galen's long-standing theories, which raised tensions between Paracelsus' followers and those who they followed the more traditional Galenic theory teachings. This animosity is not surprising because Galen has been used as a medical source for fifteen hundred years; suddenly having to confront a competing theory would be a difficult adjustment for many to make. Yes, there had been problems with Galenic theory before then, but Paracelsus' theories were the first to try to replace Galenic theories. Harkness, in his chapter "The Contest over Medical Authority", describes how most university-trained physicians disapproved of very potent chemical medicines that were considered Paracelsian, and favored Galenic cures such as bloodletting and simple purgatives based on herbs, which were thought to rebalance the body's humors, clearly demonstrating that Galenic doctors sought to improve the state of their treatments. Paracelsian cures were not the only thing under attack; Nicholas Culpeper, Paracelsian and author of English Physician, accurately describes the Galenist view held by the Paracelsians when he writes of how “He found the practice of physics directed more by the terms of art than by the principles of nature and governed more by avarice than from the principles of nature. from a genuine desire to restore health and strength to the patient who gives evidence." Of course, more traditional doctors did not remain silent; according to Culpeper, they described him as "furious and vindictive" in attempting to explain away his unique views. Their attacks only increased after it became known that Culpeper relied on astrology, a not uncommon occupation on their part, proving that they were the competent authorities on the subject or defaming Paracelsian. healers.Berthold, Andreas. The wonderful and strange effects and virtues of a new Terra Sigillata recently discovered in Germany. London: 1587.Culpeper, Nicholas. English doctor and comprehensive herbalist. London: Printed for Nicholas Culpeper. Dannenfeldt, Karl H. "The Introduction of a New Drug in the 16th Century: Silesian Earth." Medical history: 174-188. Harkness, Deborah E. “The Medical Authority Contest.” The Jewel House: Elizabethan London and the Scientific Revolution. New Haven: Yale University Press, 2007. Rankin, Alisha. "Empiria, doctors and miracle drugs in early modern Germany: the case of the panacea Amwaldina". Early Science and Medicine 14: 680-710. Print.Rankin, Alisha. Health and healing in medieval and modern Europe. Lesson