During his ten-year journey to Ithaca after fighting in the Trojan War, Odysseus and his crew came ashore at an island inhabited by the Cyclopes, a race of one-eyed giants.  When he and some of his crewmen went to seek them out, they stumbled across a cave filled with livestock and provisions, which turned out to be the abode of a Cyclopes named Polyphemus.  After sealing the entrance to the cave with a boulder, Polyphemus explained to Odysseus that the religious tradition of hospitality towards travelers meant nothing to him and proceeded to demonstrate his point by devouring four of the Greek general's crew. 

At length, Odysseus was able to blind Polyphemus by driving a stake through his eye, allowing him and the remaining crewman to escape.  As the Greeks were putting out to sea, Odysseus yelled taunts at the enraged giant, who hurled a boulder which barely missed sinking Odysseus' ship.  Although his terrified crew begged their leader to stop, he shouted a final boast to Polyphemus.  

Cyclops, if anyone asks you who it was that put your eye out and spoiled your beauty, say it was the valiant warrior Odysseus, son of Laertes, who lives in Ithaca.

Polyphemus took revenge against Odysseus by praying to his father Poseidon, the god of the sea, to either kill him or make his journey home a long ordeal. Poseidon answered his son's prayer, and in delaying Odysseus's return to his homeland with a succession of grueling challenges, taught him the foolishness of hubris, the most of dangerous of transgressions in the Hellenic cosmos.