According to tradition, they founded Tenochtitlan ( "Place of the High Priest Tenoch" ) after much wandering when they saw on an island in Lake Texcoco the sign that their god Huitzilopochtli had indicated -- an eagle perched on a cactus, eating a serpent .
The sign showed an eagle being eaten by a serpent.
( z1 show :ARG0 ( z2 sign ) :ARG1 ( z3 eat :ARG0 ( z4 serpent ) :ARG1 ( z5 eagle ) ) )