In Greek mythology, Lethe was the name of a river in the underworld that was also called "the River of Unmindfulness" or "the River of Forgetfulness." Legend held that when someone died, he or she was given a drink of water from the river Lethe to forget all about his or her past life. Eventually this act of forgetting came to be associated with feelings of sluggishness, inactivity, or indifference. The name of the river and the word lethargic, as well as the related noun lethargy, all derive from lēthē, Greek for "forgetfulness."