What imagery does the author use?How imagery can change the interpretation of a poem?

The poet metaphorically sees the fog as a living thing which visits the city, observes and then departs. He gives it a personality and so we understand the nature of this fog. It is capricious, silent, mobile and without malice. It has little feet and is invasive but in a silent and gentle way. The use of imagery has given this short poem substance and mood.