In the first grouping of lines, the speaker describes the evening "spread out against the sky / Like a patient etherized upon a table." This seems to signify a kind of fuzziness, as though the colors in the sky are diffuse and hazy, possibly the effects of air pollution. Further,...
In the first grouping of lines, the speaker describes the evening "spread out against the sky / Like a patient etherized upon a table." This seems to signify a kind of fuzziness, as though the colors in the sky are diffuse and hazy, possibly the effects of air pollution. Further, he describes the "half-deserted streets, / The muttering retreats . . . / Streets that follow like a tedious argument of insidious intent . . . " The speaker certainly doesn't describe this urban setting in a positive way. He uses a simile to describe the streets as being like an argument that goes on and on without really going anywhere, and yet they are treacherous, as though they will entrap a traveler who attempts to follow them.
Moreover, the speaker describes the "yellow fog" just outside all of the windows, referring to it, also, as "yellow smoke." The color choice, yellow, seems to imply some kind of decay or disease—perhaps in the moral fabric of society, referring to society's diminished values. Further, he describes this mist as having a back and muzzle to rub up against the window, and a tongue to lick the evening, and he says that it leaps and looks and then curls around the house to go to sleep. This sounds a great deal like a dog, but, again, it is not positive. The fog or smoke is a dirty, sordid color, and it obscures vision. The dog sounds like a nuisance, licking and laying where it is not wanted, where it is in the way. It also closes in the house, seeming almost to trap those within (like the streets).
Thus, Eliot explores the theme of urbanization by characterizing the urban setting as an overwhelmingly negative one; it's as though he gives it life and the intention to trap and suffocate. He describes the sky as someone who is drugged, the streets as though they are a ridiculous but menacing argument, the fog as a miasma of yellow that wraps around the house and blocks the windows. The overwhelming mood, then, makes us sense the vulnerability one might feel and informs us of the isolation the narrator expresses. Therefore, it is understood that urbanization, though it may draw people physically closer, only contributes to the sense of alienation Prufrock knows.