You will have heard that expression of stoic realism, it is what it is. I'm saying, it is what it isn't. The world is not a cave really nor is it a well furnished lab and we clothed in the alb of investiture, the white coat. The first is the Platonic metaphor and the second is a confection of mine own, compounded of many simples. What you have there are two examples of a series of similes that are condensed into a single metaphor. This is a common strategy of mental economy and it is operative in poetic language in which meaning is typically compressed. To dispense with metaphor is to perhaps dispense with language itself.
The most conspicuous point of contact between meaning and poetry is metaphor....... If we trace the meanings of a great many words - or those of the elements of which they are composed – about as far back as etymology can take us, we are at once made to realize that an overwhelming proportion, if not all, of them referred in earlier days to one of these two things – a solid, sensible object, or some animal (probably human) activity.(From the chapter on Metaphor in Poetic Diction by Owen Barfield.)
Displacement or replacement is what Wallace Stevens accuses himself of. He does not face up to the given in all spiritual seasons.
The Motive for Metaphor
You like it under the trees in autumn,
Because everything is half dead.
The wind moves like a cripple among the leaves
And repeats words without meaning.
In the same way, you were happy in spring,
With the half colors of quarter-things,
The slightly brighter sky, the melting clouds,
The single bird, the obscure moon—
The obscure moon lighting an obscure world
Of things that would never be quite expressed,
Where you yourself were never quite yourself
And did not want nor have to be,
Desiring the exhilarations of changes:
The motive for metaphor, shrinking from
The weight of primary noon,
The A B C of being,
The ruddy temper, the hammer
Of red and blue, the hard sound—
Steel against intimation—the sharp flash,
The vital, arrogant, fatal, dominant X.
He is, as it were, happier with glimpsing things in half light and not primary noon which is altogether too clear for his evasions. How much better it would be if he forged the smithywork of his soul using the plain indications of correct temperature namely cherry red and peacock's eye in a downright way. Forgive the twee 'smithywork' but it seems to go with a poem which finally for me does not give pleasure. Non placet then. The metaphor of the final stanza does not go on all fours when one considers that a smithy is always kept in low light the better to gauge the annealing and quenching colours.
Compare this to Yeats finding metaphors for poetry in Georgie's scribbles.
On the afternoon of October 24th 1917, four days after my marriage, my wife surprised me by attempting automatic writing. What came in disjointed sentences, in almost illegible writing, was so exciting, sometimes so profound, that I persuaded her to give an hour or two day after day to the unknown writer, and after some half-dozen such hours offered to spend what remained of life explaining and piecing together those scattered sentences. ‘No,’ was the answer, ‘we have come to give you metaphors for poetry.’How invidious is that.
Denis Donoghue does his best, his almighty best, with the poem but I sense the reservations from a man that bleeds Yeats: