Transposition is very much what poetry and all literary art is about. To hear snatches from the huge unknowable symphony of experience, to catch them and transpose them to a key that resonates with our understanding, so that at some point they harmonise with that unheard melody from heaven we are always trying to hear, that is the purpose of poetry.
In a happy coincidence, this quote from Malcolm Guite’s Faith, Hope, and Poetry speaks directly to the name of ‘Transpositions’ and to the heart of this post. Guite manages to craft an image of the purpose of poetry which is fascinating in that in describing poetry’s purpose he employs one of poetry’s most powerful tools – metaphor. As abstract and beautifully succinct as Guite’s assertion is, one concrete way in which poetry transposes is Ekphrasis.
Ekphrasis (sometimes spelled ecphrasis) is the graphic, often dramatic description of a visual work of art. In classical and ancient eras it referred to a description of any thing, person, or experience. Marjorie Munsterberg contends it is that this kind of “visual description” can be described as the “oldest type of writing about art in the West” . Musterberg explains:
The goal of this literary form is to make the reader envision the thing described as if it were physically present. In many cases, however, the subject never actually existed, making the ekphrastic description a demonstration of both the creative imagination and the skill of the writer. For most readers of famous Greek and Latin texts, it did not matter whether the subject was actual or imagined. The texts were studied to form habits of thinking and writing, not as art historical evidence. 
The word comes from the Greek ek (out) and phrasis (speak), with its verb ekphrazein, meaning to proclaim or call an inanimate object by name. In the nineteenth century, ekphrasis, was expressed in new ways. The main difference was that ekphrasis began to incorporate the point of view of the poet as viewer almost in the style of reportage with personal commentary. However, sharing an experience of the viewing of art didn’t completely change to only being about real historical experiences and identifiable artistic artifacts. Indeed, The most famous example from this period is John Keats’ “Ode to a Grecian Urn.” Munsterberg explains the shift in this way:
This shift in emphasis reflects a transformation in the genre of ekphrasis, which increasingly came to include the reaction of a particular viewer as part of the description of an object.  […] The goal of these Victorian writers was to make the reader feel like a participant in the visual experience. The more convincingly this was done, the more effective the writing was judged to be. 
An example of ekphrasis in poetry from the nineteenth century is “To A Picture by Giovanni Bellini” by E. Nesbit.
To A picture by Giovanni Bellini 
DEAR Lady, In whose I see,
All that I would and cannot be,
Let thy pure light for ever shine.
Though dimly, through this life of mine !
Though what I dream, and what I do.
In prayer’s despite are always two,
Light me, through a maze of deeds undone,
O thou whose deeds and dreams are one !
And though through mists of strife and tears,
A world away my star appears,
Yet let Death’s sunrise shine on me.
Still reaching arms and heart to thee !
Though to which painting Nesbit is responding is not clear, it is likely that it is one of Bellini’s studies of the Madonna. The Madonna was Bellini’s special study. However, which of the almost a dozen “Madonna and Child” paintings it could be is not clear. Though, strictly speaking, ekphrasis can refer to a direct comparison or experience of a specific work, in this case it may reflect the experience of a number of different Bellini paintings.
In literary terms, and especially given its classical roots and the way it came to prominence in the work of many nineteenth century poet theologians (like John Ruskin and Walter Pater), ekphrasis is rarely spoken about in relation to contemporary poetry. However, contemporary poetry is not ignorant of the ekphrastic mode. Some contemporary poets who are particularly successful in their employment of ekphrasis include Eavan Boland,Geoffrey Hill, and Les Murray. Finally, it could be said that in our reflections on the arts and in reflecting on our experiences of specific works of art, much of what Transpositions is about is ekphrastic.
Can you suggest any other examples of ekphrasis that might be helpful to this discussion?
 Marjorie Munsterberg, http://www.writingaboutart.org/pages/ekphrasis.html
 This poem was included in the 1888 collection titled Easter-tide and published by E.P. Dutton.