Annotation: Lethe, Keats' Ode to A Nightingale

Or emptied some dull opiate to the drains 

One minute past, and Lethe-wards had sunk

The Blue Grotto, by Albert Bierstadt

In Greek mythology the Lethe is the river of un-mindfulness (ameles potamos) in the underworld. Whoever drinks its waters forgets their past. It's described in one Ancient text as flowing through Hypnos' cave, where it also caused drowsiness (Hypnos is the the personification of sleep). In another text it borders Elysium.

Sources

"Lethe : Greek goddess of the underworld river of oblivion ." Theoi Greek Mythology, Exploring Mythology & the Greek Gods in Classical Literature & Art. N.p., n.d. Web. 15 June 2012. <http://www.theoi.com/Khthonios/PotamosLethe.html>.  

"Lethe." Wikipedia, the free encyclopedia. N.p., n.d. Web. 15 June 2012. <http://en.wikipedia.org/wiki/Lethe>.