Let us leave this place where the smoke blows blackAnd the dark street winds and bends (7-8)
Now we get the man part of the "man and the natural world" theme. It's men who drive the cars and work the factories that blow out black smoke, and men who pave and map the windy streets. When we read this poem, we're in a lovely mood throughout the first stanza, but when we hit these two lines it's as if someone has honked an obnoxiously loud car horn.
Past the pits where the asphalt flowers grow (9)
We can't imagine that these flowers are anything a honeybee would feed on, but all the same, they are a bit of nature creeping into the world of men. So for now, they'll just have to do.
For the children, they mark, and the children, they knowThe place where the sidewalk ends (15-16)
What we love about this line is that now, every time Shmoop walks past a chalk drawing on the sidewalk, we can't help but think that it's a secret code written by children, pointing us toward the world where the sidewalk ends.