John Keats who died at the age of twenty-five published only fifty-four poems in his lifetime.  On leaving school in 1810 he was apprenticed to a apothecary-surgeon.  His first efforts at writing poetry seem to have commenced in 1814.  In 1815 he quit his apprenticeship and became a student at Guy's Hospital. However, despite his poor finances he also left Guy's in 1816 to concentrate on poetry.

Keats has always been regarded as one of the principal figures in the Romantic movement, and despite criticism during his lifetime, his stature as a poet has steadily grown through all the changes of fashion.

His letters published in 1848 and 1878, have come to be regarded with almost as much admiration given to his poetry.  T.S. Eliot (1888-1965) described the letters as 'certainly the most notable and important every written by any English poet'.

Drabble, Margaret, editor. The Oxford Companion to English Literature. Sixth edition, Oxford University Press, 2000, pp. 550-551.        

Ode to a Nightingale (1819)

My heart aches, and a drowsy numbness pains

My sense, as though of hemlock I had drunk,

Or emptied some dull opiate to the drains

One minute past, and Lethe-wards had sunk:

'Tis not through envy of thy happy lot,

But being too happy in thine happiness -

That thou, light-winged Dryad of the trees,

In some melodious plot

Or beechen green, and shadows numberless,

Singest of summer in full-throated sense.