But when Keats calls Mercury “the star of Lethe,” the word “star” makes us see him as the poor ghosts do who are awaiting his convoy, while the word “Lethe” intensifies our sympathy by making us feel his coming as they do who are longing to drink of forgetfulness.  And this again reacts upon the word “star,” which, as it before expressed only the shining of the god, acquires a metaphysical significance from our habitual association of star with the notions of hope and promise.  Again nothing can be more fanciful than this bit of Henry More the Platonist: 

                        What doth move
  The nightingale to sing so fresh and clear? 
  The thrush or lark that, mounting high above,
  Chants her shrill notes to heedless ears of corn
  Heavily hanging in the dewy morn?

But compare this with Keats again: 

  The voice I hear this passing night was heard
  In ancient days by emperor and clown;
  Perhaps the self-same song that found a path
  Through the sad heart of Ruth when, sick for home,
  She stood in tears amid the alien corn.

The imagination has touched that word “alien,” and we see the field through Ruth’s eyes, as she looked round on the hostile spikes, not merely through those of the poet.

CRITICAL FRAGMENTS

I. LIFE IN LITERATURE AND LANGUAGE

It is the office and function of the imagination to renew life in lights and sounds and emotions that are outworn and familiar.  It calls the soul back once more under the dead ribs of nature, and makes the meanest bush burn again, as it did to Moses, with the visible presence of God.  And it works the same miracle for language.  The word it has touched retains the warmth of life forever.  We talk about the age of superstition and fable as if they were passed away, as if no ghost could walk in the pure white light of science, yet the microscope that can distinguish between the disks that float in the blood of man and ox is helpless, a mere dead eyeball, before this mystery of Being, this wonder of Life, the sympathy which puts us in relation with all nature, before that mighty circulation of Deity in which stars and systems are but as the blood-disks in our own veins.  And so long as wonder lasts, so long will imagination find thread for her loom, and sit like the Lady of Shalott weaving that magical web in which “the shows of things are accommodated to the desires of the mind.”

It is precisely before this phenomenon of life in literature and language that criticism is forced to stop short.  That it is there we know, but what it is we cannot precisely tell.  It flits before us like the bird in the old story.  When we think to grasp it, we already hear it singing just beyond us.  It is the imagination which enables the poet to give away his own consciousness in dramatic poetry to his characters, in narrative to his language, so that they react upon us with the same original force as if they had life in themselves.