Rush was a leader of the American Enlightenment and an enthusiastic supporter of the American Revolution. He was a leader in Pennsylvania's ratification of the Constitution in 1788. He was prominent in many reforms, especially in the areas of medicine and education. He opposed slavery, advocated free public schools, and sought improved education for women, and a more enlightened penal system. As a leading physician, Rush had a major impact on the emerging medical profession. As an Enlightenment intellectual, he was committed to organizing all medical knowledge around explanatory theories, rather than rely on empirical methods. Rush argued that illness was the result of imbalances in the body's physical system and was caused by malfunctions in the brain. His approach prepared the way for later medical research, but Rush himself undertook none of it. He promoted public health by advocating clean environment and stressing the importance of personal and military hygiene. His study of mental disorder made him one of the founders of American psychiatry. In 1965 the American Psychiatric Association recognized Rush as the "father of American psychiatry".