Is it ensure, insure, or assure?
demigod (son of the Titan Iapetus) who made man from clay and stole fire from heaven and taught mankind its use, for which he was punished by Zeus by being chained to a rock in the Caucasus, where a vulture came every day and preyed on his liver. The name is Greek, and anciently was interpreted as literally "forethinker, foreseer," from promethes "thinking before," from pro- "before" (see pro-) + *methos, related to mathein "to learn," from enlargement of PIE root *men- "to think" (see mind (n.)). However Watkins suggests the second element is possibly from a base meaning "to steal," also found in Sanskrit mathnati "he steals."
In classical mythology, the Titan who stole fire from the gods and gave it to humans. As punishment for the theft, Zeus ordered Prometheus chained to a rock and sent a great eagle to gnaw at the Titan's liver. Despite his torment, Prometheus refused to submit to Zeus' will. He was eventually rescued by Hercules.