In contrast to metaphysics and rationalism, the Scottish philosopher David Hume (1711-1776) seeks to apply the experimental method, which has been successfully utilized in the natural sciences, to the exploration of human nature. His meticulous focus on observation and experience, however, unexpectedly leads him to skepticism, a form of philosophy that can be thought but not lived. According to Hume, it should not be reason, but nature that serves as the ultimate standard of our thinking, feeling, and acting. Based on this conception, the introduction discusses Hume's innovative contributions to the theory of knowledge, moral philosophy, aesthetics, and the philosophy of religion, which still deserve systematic interest today.