A symbol from Greek myth representing how desire can never be satisfied.
"...Tantalus came and lived with the gods, and was permitted to ask for whatever he desired. But the man was so immoderately given to pleasures that he asked for these and for a life like that of the gods. At this Zeus was annoyed, but fulfilled his prayer because of his own promise; but to prevent him from enjoying any of the pleasures provided, and to keep him continually harassed, he hung a stone over his head which prevents him from ever reaching any of the pleasant things near by." —Greek fragment
"There [in hell] was Tantalus, who stood in a pool, his chin level with the water, yet he was parched with thirst, and found nothing to assuage it; for when he bowed his hoary head, eager to quaff, the water fled away, leaving the ground at his feet all dry. Tall trees laden with fruit stooped their heads to him, pears, pomegranates, apples, and luscious figs; but when with a sudden grasp he tried to seize them winds whirled them high above his reach." —Bullfinch's Mythology