How does the author use allusion in the poem, Ode to a Nightingale?

Keats borrows from the lexicon of Greek and European mythology throughout the poem. In stanza 1 he refers to Lethe, the river of forgetfulness that flows through the mythical Greek underworld, and calls the nightingale a “Dryad” (7) or tree-spirit in Greek mythology. Wine in stanza 2 he dubs “the blushful Hippocrene” (16), also from the canon of Greek myth, comparing wine to the waters of the stream said to inspire poetry. Finally, he refers to “Fays” (37) and “faery lands” (70), both references to the fairies of European folklore. Keats’s use of this vocabulary ties his speaker’s monologue to the classical tradition and establishes the erudition of his speaker. It also shows the speaker operating in the world of fantasy, preempting his own doubts about the reality of his experience he will have at the end of the poem when he asks whether he has been in a “waking dream” (79) or if he is perhaps even asleep.