"Next, then," I said. "make an image of our nature in its education and want of education, likening it to a condition of the following kind. See human beings as though they were in an underground cave-like dwelling with its entrance, a long one, open to the light across the whole width of the cave. They are in it from childhood with their legs and necks in bonds so that they are fixed, seeing only in front of them, unable because of the bond to turn their heads all the way around. Their light is from a fire burning far above and behind them. Between the fire and the prisoners there is a road above, along which we see a wall. built like the partitions puppet-handlers set in front of the human beings and over which they show the puppets".

http://www.ship.edu/~cgboeree/platoscave.html
Plato's allegory of the cave: Book VI of the Republic
 
http://www.wsu.edu/~dee/GREECE/ALLEGORY.HTM
Another Link of Plato's cave allegory

http://www.simons-rock.edu/~edw/cave/
Ed Misch's Philosophy Web Site
 
http://cns-alumni.bu.edu/pub/slehar/webstuff/pcave/gestalt_model.html
A New Gestalt Model

http://rivertext.com/weil4.html
Mixing Art & Ideas

http://www.vrc.iastate.edu/why.html
Why call it Plato's Cave

http://www.uh.edu/~cfreelan/courses/cave.html
A film update of Plato's Cave?