Critique of Pure Reason

“Kant asks what reason can know without experience, and answers with a 'Copernican revolution': space and time are forms of our intuition, and the categories, such as cause and substance, are rules of our understanding, so that we can know the world a priori as it appears to us — but never as it is in itself. Reason's attempts to know the soul, the world as a whole, and God end in illusion; and so knowledge is limited, to make room for faith.”