Optical illusions are carefullly crafted artifacts and illustrations intended to deceive whoever is viewing them. Sometimes they exist in nature (animal camouflage comes to mmind). At other times they suggest the existence of the impossible in nature (see Waterfall or Ascending and Descending by M. C. Escher). They make the present seem absent or the equal. seem unequal.
This page was last modified by mgosselin on 10/08/2005