Immanuel Kant (1724-1804) was a German philosopher who is considered the central figure of modern philosophy. Kant argued that fundamental concepts of the human mind structure human experience, that reason is the source of morality, that aesthetics arises from a faculty of disinterested judgment, that space and time are forms of our sensibility, and that the world as it is "in-itself" is unknowable. He never married. He was a popular teacher. Kant always cut a curious figure in his lifetime for his rigorously scheduled habits. Kant lectured on anthropology for over 25 years.