Circe described Skylla and Charybdis to Odysseus:
Skylla is a sea monster with six heads which eats men, and Charybdis is a whirlpool that absorbs the sea and belches it back out three times a day.
Circe advises Odysseus to sorround the cliff of Skylla and sacrifice six men instead of running the risk of losing his entire ship to Charybdis. Also, he should move as quickly as possible and avoid fighting her.
Odysseus is in doubt, since he would rather not lose any men, but Circle tells him not to tell his crew. He ruefully decides to go on with the mission, and assumes this loss is a neccesary evil. However, he could have told his men, priorizing honesty above everything, and perhaps they would have carried on and died with honor. His decision can be taken as one of a leader, justifying his actions for the sake of his duty, or as one of an individual who selfishly wants to save himself.
