"Preludes" begins with a juxtaposition. The first line establishes an almost romantic tone by personifying the "winter evening" as settling down and relaxing, which might lead the reader to expect a poem focused on the calming joys of nature. However, line 2 goes immediately in another direction, evoking quite the opposite: the "smell of steaks in passageways" is something resolutely urban. The abrupt third line—"Six o'clock."—then brutally cuts short any illusions of this being a reflective nature poem. Instead, it's located firmly within a modern industrialized city, with routines structured around the clock.
The poem thus almost immediately destabilizes readers' expectations. In a way, the poem positions its readers in a state similar to that of the people the poem will go on to describe—a state in which they lack control over their own lives and feel swept up by the bustling city surrounding them.
The fourth line—"The burnt-out ends of smoky days."—echoes the second line's images of steaks cooking, which produce smoke, with its metaphor comparing "smoky" evenings to the "burnt-out ends" of cigarettes. This is also the first reference to trash in the poem, which views urban life primarily as composed of what is thrown away, rather than what is created. The heavy use of sibilance in these lines ("settles ... smell ... steaks ... passageways ... Six ... smoky days") mimics the sizzling sound of steaks frying as well as the inhalations and exhalations of smokers, positioning the reader among the city-sounds being described.
The meter of lines 1, 2, and 4 is iambic tetrameter. This means there are four iambs per line, a.k.a. poetic feet that follow an unstressed-stressed beat pattern. For example, here is the breakdown of line 1:
The win- | ter eve- | ning set- | tles down
As with the natural imagery in line 1, perhaps this relatively familiar meter is meant to lull the reader into a false sense of security—to make readers think they're getting into a classical, regularly structured poem. It may also be meant to imitate the repetitive routines seen as essential to city life. However the short line 3 violently disrupts this rhythm and is just the first of many such lines to do so, indicative of the way that the structure of urban life—with its designated working hours—interrupts natural rhythms.