Music has been used as a healing implement for centuries. Apollo is the ancient Greek god of music and of medicine and his son Aesculapius was said to cure diseases of the mind by using song and music. By 5000 BC, music was used for healing by Egyptian priest-physicians. Plato said that music affected the emotions and could influence the character of an individual. Aristotle taught that music affects the soul and described music as a force that purified the emotions. Aulus Cornelius Celsus advocated the sound of cymbals and running water for the treatment of mental disorders. Music as therapy was practiced in the Bible when David played the harp to rid King Saul of a bad spirit (1 Sam 16:23). As early as 400 B.C., Hippocrates played music for mental patients. In the thirteenth century, Arab hospitals contained music-rooms for the benefit of the patients. In the United States, Native American medicine men often employed chants and dances as a method of healing patients. The Turco-Persian psychologist and music theorist al-Farabi (872–950), known as Alpharabius in Europe, dealt with music for healing in his treatise "Meanings of the Intellect", in which he discussed the therapeutic effects of music on the soul. In his "De vita libri tres" published in 1489, Platonist Marsilio Ficino gives a lengthy account of how music and songs can be used to draw celestial benefits for staying healthy. Robert Burton wrote in the 17th century in his classic work, "The Anatomy of Melancholy", that music and dance were critical in treating mental illness, especially melancholia.