He's sitting on the stoop of a great skyscraper in the middle of a bustling metropolis. People are standing all around him, trying to help. They don't know what's wrong. This man is sitting in the middle of the city screaming and crying and they don't know why. Then the scene switches to what the man sees.
Madness is just like that.
You see the end of the earth and it hurts all around you. Its like you're wearing a space helmut with a panoramic screen that faces in. And on this screen is projected the contents of your unconscious mind in full sensory fullness and colour. Outside of that wall of illusion lies the consensual truth and it mixes with the distortion of your mind. Like colours mix on an artists palate, till you can't distinguish one from the other.