" is the name of a popular woodcut
created by M.C. Escher
. The illustration is centered on three staircases
in a triangular arrangement, each one perpendicular
to the others in three-dimensional
men and women are walking up and down these stairs past each other, but every one seems to use a different direction for "down
" -- so that one's wall
is another's floor
. One part of the illustration even has two men descending a staircase perpendicular to each other.
This illustration was popular in the 1960s and 1970s because of its psychedelic effect, but it can be seen as having a deeper metaphor -- that of different people living in different worlds side-by-side. One may consider an act good that another right next to him would think of as bad; one may think that progress is in this direction, another that it's over that way instead. But the figures in the woodcut live side by side, going about their activities, cooperating with those who agree with their sense of "up" and allowing those who don't to continue on their own way.