What Greek myth is retold in John Keats’s Endymion?

John Keats’s poem Endymion retells the Greek legend of the love between the moon goddess—referred to by Keats as Cynthia and identified in mythology as Selene, Diana, or Artemis—and Endymion, a mortal shepherd.1

While the traditional myth focuses on the goddess’s love for the youth, whom she visited while he slept in a cave on Mount Latmus, Keats shifts the emphasis to Endymion’s own longing for the goddess. In the poem, Keats transforms the narrative to explore the Romantic theme of seeking an ideal love in reality, eventually equating Endymion’s romantic pursuit with a broader quest for unity with all creation.123