In the poem ‘Fog’, the poet uses an interesting metaphor to describe an element of nature. He indirectly compares fog to a cat by presenting the idea that the movements of the fog are much like that of a cat. It enters a city silently without letting anyone know, just like the stealthy movement of a cat. Then it spreads over the entire city, just like a cat sits for a while in one place and watches its surroundings. Finally, the fog also leaves the city quietly like a cat. In this way, the poet accurately captures the nature of fog by comparing it to a cat.