How does Ezra Pound use absence in his 1913 poem 'In a Station of the Metro'?

As a key poem of the Imagist movement, it is important for us first to consider how Pound's sparsity demonstrates something that more traditionally poetical examples of poetry cannot. You will probably be struck immediately by the brevity of this poem. The use of concise language in art became for the Imagists, rebelling against the decadence of the previous century's prioritisation of Romanticism, not just a means of differentiating their art, but of bringing art closer to what they believed to be 'the truth'. As the American poet Stanley Cooperman put it, the primary aim of Imagism was "that the object, the thing, the experience-in-itself, stated boldy and without rhetorical flourish, would recreate truth". We can see this attempt in Pound's poem: note firstly the absence of a speaker. In contrast to some nineteenth-century Romanticism you might be studying (for example, William Wordsworth's "I Wandered Lonely as a Cloud"), there is no obvious subjective perspective here - Pound presents the poem as though it were an objective event, as though the metaphor he employs is somehow inherent within what is described. There is no "I", there are no characters as such; the effect here is to create an air of poetic isolation, of an 'experience-in-itself", unmediated by a poetic voice. Indeed, Pound says as much - in his reflections on the compositional process in 1916, he describes the poem as an "equation", written in "a language of colour", as opposed to a language of words. This is certainly a tricky idea to wrap one's head around. What can Pound mean by suggesting that he is moving away from a language of words? Again, it becomes useful to consider what isn't here. There is no continuous run of words - if you are looking at the poem as originally published in Harriet Monroe's little magazine Poetry, you will see how Pound places extra space between "The apparition" and "of these faces", between "Petals" and "on a wet, black". The separation of these words serves to harden them, to make them feel like separate units, and so to force the reader to confront the process behind the poem's composition, that being the mechanical stitching together of impressions. More than that, Pound's use of space forces us to slow our reading, to rupture its metre, and thus to consider the difficulties with which the poet must wrestle to capture in language their ideas. Pound's use of space also betrays what we might consider ordinary English syntax. Taken in isolation, none of these phrases make syntactical sense; for example, "of these faces" has both a preposition and a noun, but lacks a verb - it feels as though the verb of the overarching sentence is contained in one of the other phrases, but it isn't. The poetry here is, as Pound says, like an "equation", and it is specifically through his use of absence that he captures this mathematical aesthetic.