As a young man and a student, Kant lived a life of poverty and deprivation. He often went hungry, but preserved his health by "breathing only through my nose in the winter and keeping the pneumonia winds out of my chest by refusing to enter into conversation with anyone." Barely 5 feet tall, he was to become one of the giants of philosophy.
Reading the works of Scottish philosopher and skeptic David Hume awakened him, he said, from his "dogmatic slumber." His best known book is The Critique of Pure Reason, sometimes described as a nearly unreadable masterpiece of philosophy. Kant himself described it as "dry, obscure, contrary to all ordinary ideas, and on top of that prolix." (Prolix means verbose.) He was right. He once sent the completed manuscript to a friend who was himself an eminent scholar. The man read some of the book but returned it unfinished, explaining, "If I go on to the end, I am afraid I shall go mad."
Born in Konigsberg, Prussia, Kant never left town. He took a walk every day with such regularity (at 3:30 in the afternoon) that people could set their clocks by him. In his philosophical work, he tried to restrict reason to make room for faith. He believed that theoretical reason can't reach beyond the world of experience, and so he disliked the traditional "proofs" of the existence of God. He wanted instead to make religious belief a matter of "practical reason."
Kant's most famous distinction was his idea of the phenomenal world (things as they appear to us) and the noumenal world (things as they are in themselves).
Kant once wrote, "Morality is not properly the doctrine of how we may make ourselves happy, but how we may make ourselves worthy of happiness." His well-known and unduly severe conception of morality: acting on the motive of duty alone. His principle of universalizability in ethics is often alluded to by the common question: "What if everybody did it?"
