Although it is a quality of the imagination that it seeks to place together those things which have a common relationship, yet the coining of similes is a pastime of very low order, depending as it does upon a nearly vegetable coincidence. (p. 18) 
Taken from the Prologue to William Carlos Williams’ prose-poetry sequence, Kora in Hell: Improvisations, the epigraph above constitutes a denigration of what the poet sees as the fast and cheap “easy lateral sliding” of simple comparison. It is an idea that might stand in as a guiding principle for readers of his poetry in general. For Williams, neither metrics nor rhythms suffice to make a poem; furthermore, a line that links a pretty flower and a paramour amounts to nothing more than sentimental valuation. Rather, poetry thrives when the poet properly uses imagination as a means to “[discover] in things those inimitable particles of dissimilarity to all other things which are the peculiar perfections of the thing in question.” (p. 18)
Williams was a physician of the body before he was a poker and prodder of American poetics. In his writing he displays the grotesque but denies justification to those who squirm at that grotesqueness; snails, though slimy when alive, are a symbol of delicacy when cooked and simmered in butter. Aware of the fragility of life, and of the difficulty for even the very hardy, the wise know not to spread resources thin, know to cultivate only what’s necessary. A stripper of artifice, and excess, the poet must know when to cut away the prodigal line:
Fools have big wombs. For the rest? – here is penny-royal if one knows to use it. But time is only another liar, so go to the wall a little further: if blackberries prove bitter there’ll be mushrooms, fairy-ring mushrooms, in the grass, sweetest of all fungi. (31)
Delay, time’s consort, may seem to disrupt or distort expectation, but the unexpected has its peculiar benefit, if you look for it.
Recall the Modernist elevation of the New, alluded to by Williams here: “If a thing have novelty it stands intrinsically beside every other work of artistic excellence.” (p. 23) It is toward the novelty of things that the poet must look for inspiration; to strive to present certain peculiarities only as they relate to themselves is the goal. To know that this perfection is latent in all things, that all things change, that too, and everything as well is more itself, rather improvisatory.
There is nothing sacred about literature, it is damned from one end to the other. There is nothing in literature but change and change is mockery. (p. 13)
The syllogism here implies something unintended, and that is that Williams does not take himself seriously, that he sees his work as that of a heckler. But the target of his mockery is not literature, but makers of literature who attempt a long-term stasis, who seek to realign the medium’s codifications to follow along the foundations of their own work. He is aware of the modifications done to any particular meaning by time and usage, and is aware that “the gist” of poetry “makes logic a butterfly.” (p. 81)
The dumb cluck of a wild tom belies his ferocity, capable of outflanking the wisdom of the blackbird, whose greed it is to swoop for young eggs, a heckler in the midst of a chaotic lawn. There is seed to be had, and seed to go round, but it soothes the worrier to rush through folly, and nature is pretty until it becomes a nuisance of deterrence and upkeep. There is a panhandler – “he wanders the same subway platforms every day, his favorite spot is right there, where hot air blasts up, vented” – who sits the same sit every day and banters for a living while arabesques curlicue his beard and blackbirds’ feet make deep cuts around his eyes.
Vegetable coincidence, the tendency to affix easy similarities to things when they are comparable, objects, ideas, is the heaviness that hulks over so much bad poetry. Its opposite is the ever-urging present, inimitable and unrecorded, plenteous and plentiful, that is the summation – for gain or loss – of all the novelty that has ceased to be novel, the innovations of inert energy, beggars, sappers.
 Williams, William Carlos. Imaginations. Prologue to Kora in Hell: Improvisations. New York: New Directions Books, 1970.