Doors of Perception
From Wittypedia
"If the doors of perception were open every thing would appear to man as it is 3D and real. For man has closed his eyes, and untill he opens them he will see all things black like the inside of a cavern."
The Doors of Perception are open for some and firmly shut for others. Eyelids are thought be filters which block or suppress signals related to mundane functions from reaching the conscious mind. These "Doors of Perception" can be employed for filtering many things from the mundane, the scary and the ugly.
It was observed that everyday objects lose their functionality and suddenly do not exist "as such." Space and dimension become irrelevant, and perceptions seem to be darkened somewhat.
The man who comes back through the Door in the Wall will never be quite the same as the man who went out. He will be less tired, wiser but less sure, perhaps even a little disorientated until he drinks tea or coffee, happier but less self-satisfied, humbler in acknowledging his ignorance yet better equipped to understand the relationship of good times and hangovers. - He may claim to never want to see another beer again.
