Keats is an all-time favorite poet (one of my "Overdue Reads" books is The Complete Poems and Selected Letters of John Keats). There are so many poems I could choose - "La Belle Dame Sans Merci", "Ode to a Nightingale", "Hyperion", "To Autumn" - but I picked the one that breaks my heart every time I read it.
"Bright Star" is Fanny Brawne, the young woman who loved Keats, and who loved her back, yet they could never be together because of Keats's terminal case of tuberculosis. How many poems would Keats have written, children he may have passed his gift to, had he not died in Rome at the age of twenty-five? "Bright Star" was written some time in 1819-1820 and the final revisions done on his way to Rome, never to see Fanny again.
Bright star, would I were stedfast as thou art--
Not in lone splendour hung aloft the night
And watching, with eternal lids apart,
Like nature's patient, sleepless Eremite,
The moving waters at their priestlike task
Of pure ablution round earth's human shores,
Or gazing on the new soft-fallen mask
Of snow upon the mountains and the moors--
No--yet still stedfast, still unchangeable,
Pillow'd upon my fair love's ripening breast,
To feel for ever its soft fall and swell,
Awake for ever in a sweet unrest,
Still, still to hear her tender-taken breath,
And so live ever--or else swoon to death.