This text comes from The Poetical Works of John Keats, a historical songbook transcribed on Wikisource and reproduced from the pinned revision linked below.
Haydon! forgive me that I cannot speak
Definitely of these mighty things;
Forgive me, that I have not eagle's wings,
That what I want I know not where to seek.
And think that I would not be over-meek,
In rolling out upfollowed thunderings,
Even to the steep of Heliconian springs,
Were I of ample strength for such a freak.
Think, too, that all these numbers should be thine;
Whose else? In this who touch thy vesture's hem?
For, when men stared at what was most divine
With brainless idiotism and o'erwise phlegm,
Thou hadst beheld the full Hesperian shine
Of their star in the east, and gone to worship them!