I have been reading ...

... and reading Keats's "Ode to a Nightingale," quite simply because it is immensely rewarding to do so. Long before the French symbolists, Keats had achieved an almost pure linguistic music: Quite simply, he combines his words in the most perfectly melodic manner.

Consider:

O for a draught of vintage! that hath been
Cool'd a long age in the deep-delvèd earth,
Tasting of Flora and the country-green,
Dance, and Provençal song, and sunburnt mirth!
O for a beaker full of the warm South!
Full of the true, the blushful Hippocrene,
With beaded bubbles winking at the brim,
And purple-stainèd mouth;
That I might drink, and leave the world unseen,
And with thee fade away into the forest dim:

You need to say it aloud. In fact, it is best to memorize it, so that you can just say it and shape it as you would a musical composition. Consider the magical precision of the words - "a draught of vintage," "a beaker full of the warm South," "beaded bubbles winking at the brim ..."

Or this:

Fade far away, dissolve, and quite forget
What thou among the leaves hast never known,
The weariness, the fever, and the fret
Here, where men sit and hear each other groan;
Where palsy shakes a few, sad, last grey hairs,
Where youth grows pale, and spectre-thin, and dies;
Where but to think is to be full of sorrow
And leaden-eyed despairs;
Where beauty cannot keep her lustrous eyes,
Or new Love pine at them beyond to-morrow.

Again, this is language to be savored. Keats was 23 when he wrote the poem. Soon he would himself grow pale and spectre-thin and die. He had already witnessed that happen to his brother Tom, but it would be another year before he himself would cough up blood and notice its ominous color ("I know the color of that blood; it is arterial blood. I cannot be deceived. That drop of blood is my death warrant." )

There does seem to be a premonition of death in this poem:

Darkling I listen; and, for many a time
I have been half in love with easeful Death,
Call'd him soft names in many a musèd rhyme,
To take into the air my quiet breath;
Now more than ever seems it rich to die,
To cease upon the midnight with no pain ...

Keats was remarkable man, I think perhaps the sharpest thinker of all the romantics (Coleridge thought a lot and often brilliantly, but ...) He was certainly his own man:

The common cognomen of this world among the misguided and superstitious is "a vale of tears" from which we are to be redeemed by a certain arbitrary interposition of God and taken to Heaven. What a little circumscribed straightened notion!
Call the world, if you please, "the Vale of Soul Making". Then you will find out the use of the world....
There may be intelligences or sparks of the divinity in millions -- but they are not Souls till they acquire identities, till each one is personally itself.
Intelligences are atoms of perception -- they know and they see and they are pure, in short they are God. How then are Souls to be made? How then are these sparks which are God to have identity given them -- so as ever to possess a bliss peculiar to each one's individual existence. How, but in the medium of a world like this?
This point I sincerely wish to consider, because I think it a grander system of salvation than the Christian religion -- or rather it is a system of Spirit Creation...
I can scarcely express what I but dimly perceive -- and yet I think I perceive it -- that you may judge the more clearly I will put it in the most homely form possible. I will call the world a school instituted for the purpose of teaching little children to read. I will call the human heart the hornbook used in that school. And I will call the child able to read, the soul made from that school and its hornbook.
Do you not see how necessary a world of pains and troubles is to school an intelligence and make it a soul? A place where the heart must feel and suffer in a thousand diverse ways....
As various as the lives of men are -- so various become their souls, and thus does God make individual beings, souls, identical souls of the sparks of his own essence.
This appears to me a faint sketch of a system of salvation which does not affront our reason and humanity...

The foregoing letter is quoted on this post of Dr. Ed Friedlander: Enjoying "La Belle Dame Sans Merci", which has some further information regarding the arterial blood quote. Dr. Friedlander also has an interesting comment on letter quoted:

Keats believed that we begin as identical bits of God, and acquire individuality only by life-defining emotional experiences. By doing this, we prepare ourselves for happiness in the afterlife.
You may decide for yourself (or exercise negative capability) about whether you will believe Keats. But it's significant that this most intimate explanation of the personal philosophy behind his work follows a powerful lyric about emotional devastation.
If Keats's philosophy is correct, then any intense experience -- even letting your life rot away after a failed relationship, or enduring the agony of heroin withdrawal, or dying young of tuberculosis -- is precious. (Perhaps Keats, medically trained and knowing he had been massively exposed, was foreseeing his own from TB -- he would have been pale and sweaty and unable to move easily.) Each goes into making you into a unique being.
The idea is as radical as it sounds. And if you stay alert, you'll encounter similar ideas again and again, in some of the most surprising places.

In case you forget what "negative capability" is, here is how Keats explains it:

"I mean Negative Capability, that is when man is capable of being in uncertainties, Mysteries, doubts without any irritable reaching after fact & reason." I should have quoted this long ago, since it is my characteristic mental outlook. Are you there, Noel?