Pauling was also an author and a teacher. His first book, "The Nature of the Chemical Bond" (1939), is still used today. his introductory textbook, "General Chemistry" (1949). Later in life, he became an advocate for greatly increased consumption of vitamin C and other nutrients. He generalized his ideas to define orthomolecular medicine, which is still regarded as unorthodox by conventional medicine. He popularized his concepts, analyses, research and insights in several successful but controversial books, such as "How to Live Longer and Feel Better" in 1986.