"If the doors of perception were cleansed every thing would appear to man as it is: Infinite. For man has closed himself up, till he sees all things thro' narrow chinks of his cavern."

Aldous Huxley had a similar intuition in his essay, The Doors of Perception: the body perceives everything, and environment (including culture, traditions etc.) teaches the man to close some doors lest he be overwhelmed. Mescaline and other entheogens are a way to open most of the doors. Artists (such as Van Gogh) are people with a different set of doors open/closed.