He knew how to hob-nob with the Gods and could tell anything by the flight of birds if there were no Gods around. CALCHAS knew who had the bow of HERACLES and claims the Wooden Horse idea was all his idea.
Preening himself on his return home, something unpredictable happened. He was stranded on the Ionian coast. Here he met MOPSUS, another seer, who had predicted his coming and proved to be ten times smarter.
CALCHAS, whose professional dignity suffered a mortal blow, died of sorrow. As predicted.
See also the Etruscan CHALCHAS.