This text comes from The Poetical Works of John Keats, a historical songbook transcribed on Wikisource and reproduced from the pinned revision linked below.
O THOU! whose face hath felt the Winter's wind,
Whose eye hath seen the snow-clouds hung in mist,
And the black elm-tops among the freezing stars
To thee the Spring will be a harvest-time.
O thou, whose only book hath been the light
Of supreme darkness, which thou feddest on
Night after night, when Phœbus was away,
To thee the Spring shall be a triple morn.
O fret not after knowledge!—I have none,
And yet my song comes native with the warmth.
O fret not after knowledge!—I have none,
And yet the Evening listens. He who saddens
At thought of idleness cannot be idle,
And he's awake who thinks himself asleep.