In the Spring of 1817, John Keats, then still a little-known poet, set out to write at least forty lines of poetry every day. The result was Endymion. This retelling of the Greek myth has long been celebrated as one of Keats' breakthrough poems, and though throughout the poem it is clear that some days were filled with inspiration, and others were not, the poem's four books filled with adventure and romance remain a great work of one of the 19th century's greatest poets.

Endymion is a poem by John Keats first published in 1818 by Taylor and Hessey of Fleet Street in London. It begins with the line "A thing of beauty is a joy for ever". Endymion is written in rhyming couplets in iambic pentameter.