By line 3 we notice the fog isn't moving anymore. It's sitting and "looking" over the harbor and city, which tells us it's covering more space now. So it's not just on its way anymore. It's here.
We can also feel a passing of time that's occurred since we're now at the start of a new line that indicates a change in the appearance of the fog. It's almost as if we've moved with it.
When we imagine the metaphor of a fog looking catlike, we can actually see the fog here "sitting" as a cat would, kind of sprawled out a bit (depending on how many treats it's had) and taking up way too much room on the foot of our bed, so to speak.
So by now the fog is hovering over the harbor and city checking out the scenery as a cat might. We know that fog tends to accumulate a lot more near harbors, adding to that sitting, catlike shape it seems to have once it's settled over an area.
There's more enjambment too between lines 3 and 4, which just like last time, keeps the flow of the metaphor and image without any distractions that come with punctuation. No stops, no pauses.
What about the mood? Is there something ominous, maybe even frightening about these lines? We can almost feel it watching us, even if we're not there. It's "over" us which adds to that looming, impending sense of uncertainty and perhaps fear. When things are "over," or above us, we tend to feel more vulnerable.
And again, just like a cat, we're not sure what that fog will do. It could pounce at any moment or just slink away into the shadows. But since it's "looking" over us, we get the sense that there is a possibility of danger in its presence.
The word "city" also gives the impression that we're not the only ones vulnerable to that fog. There are many more people there too who may be just as anxious and curious as to what the fog will do next. Check out the "Setting" section for more.
on silent haunches and then moves on.
Sandburg is extending the metaphor of the fog looking catlike by including this line of it sitting and looking "on silent haunches." Haunches are kind of like a cat's thighs, and they're the parts that enable kitty to jump and pounce as far as she'd like to.
Notice too the repetition of the word "on" that we saw first in line 2 and see again here in line 5. It seems the speaker is really keeping the metaphor of the cat-fog together by reminding us that the two are fused into this one image. The fog is "on" little cat feet and "on" silent haunches.
What do we make of the image of "silent haunches?" Maybe the word "silent" adds to the mysterious ways of the fog and its unpredictability. And perhaps the word "haunches" reminds us of the possibility of it moving in a quick, powerful, and equally unpredictable way. Put them together and we got ourselves a powerful and potentially dangerous weather system that may be a symbol for some bigger ideas. Check out "Symbols and Imagery" for more.
We get more enjambment too in these lines. In fact, the entire second half of the poem is combined into one continuous image and thought. Check out "Form and Meter" for more.
The line break between 5 and 6 heightens our sense of anxiety as to what the fog will do next. Maybe it will pounce on our heads, maybe it will move on. But that break nonetheless makes us pause and dangles all possibilities over our heads.
By line 6 we learn that the cat-fog is on the move again. Sigh of relief. It's using those "silent haunches" to move elsewhere, though we're not sure what the point of destination is. But we do know it's moving and could pounce on another harbor/city if it chooses to.
Consider though the dramatic change of mood that occurs between these last two lines. Within seconds we go from feeling anxious to somewhat relieved.
So how the heck did Sandburg manage to do all of this in only two lines? It's not just because the guy's a poetry wiz…
If we take a step back and consider all of the devices we've made note of, we begin to see that the effect is a combination of simple and yet poignant words that create a sense of unpredictability, danger, and power: "silent haunches." Then he has a line break that heightens our sense of anxiety and wonder. And finally we get that concluding image of the cat-fog moving on while we breathe a sigh of relief.
So not only do we end the poem with an awesome image/metaphor in mind, but we also feel as if we've been taken for an emotional rollercoaster that lasted all of ten seconds.
We may also think about all of the things that happen in our lives in the same sort of way that the fog seems to creep up on us and then suddenly disappear.
Check out "Themes" for more on that idea.
And last, but not least, we notice the repetition of that word "on" again at the very end of line 6. Sandburg appears to be keeping his metaphor very neat and solidly fused into this one image of a cat-fog. It looks like a cat and "moves on" as cat. There's no deviating from that image which makes the entire poem resonate in our minds even more.