About 1564, the curriculum was changed to two terms of grammar, four terms of rhetoric, five terms of dialectic (examining ideas, opinions logically), three terms of arithmetic, and two terms of music. There were now negative numbers, irrational numbers, and imaginary numbers. Also available were astrology, and alchemy, cultivation of gardens, and breeding of stock, especially dogs and horses. Astronomy, geometry, natural and moral philosophy, and metaphysics were necessary for a master's degree. The university libraries of theological manuscripts in Latin were supplemented with many non-religious books. There were graduate studies in theology, medicine, music, and law, which was a merging of civil and canon law together with preparatory work for studying common law at the Inns of Court in London. In London, legal training was given at the four Inns of Court. Only young gentry were admitted there and many later became members of Parliament or Justices of the Peace. It took about seven years there to become a lawyer. Besides reading textbooks in Latin, the students observed at court and did work for practicing lawyers. They often also studied and attended lectures on astronomy, geography, history, mathematics, theology, music, navigation, foreign languages, and lectures on anatomy and medicine sponsored by the College of Physicians. A tour of the continent became a part of every gentleman's education. Medical texts were Hippocrates and Galen. These viewed disease as only part of the process of nature, without anything divine. They stressed empiricism, experience, collections of facts, evidences of the senses, and avoidance of philosophical speculations. Galen's great remedies were proper diet, exercise, massage, and bathing. He taught the importance of a good water supply and good drainage. Greek medicinal doctrines were assumed, such as preservations of the health of the body was dependant on air, food, drink, movement and repose, sleeping and waking, excretion and retention, and the passions. It was widely known that sleep was restorative and that bad news or worry could spoil one's digestion. An Italian book of 1507 showed that post-mortem examinations could show cause of death by gallstones, heart disease, thrombosis of the veins, or abscesses. Because physicians were allowed to dissect corpses, there were anatomy textbooks and anatomy was related to surgery. The compound microscope was invented about 1590. A visit by a doctor cost 13s.4d. Melancholia, which made one always fearful and full of dread, and mania, which made one think he could do supernatural things, were considered to be different types of madness from infirmities of the body. Barber-surgeons extracted teeth and performed surgery. Barbers were allowed to do only dentistry and bleeding. A College of Surgeons was founded. Teachers of surgery used corpses of felons to teach anatomy. Even the poor were buried in coffins.