"Fog" is a six-line poem divided into two stanzas. It is a free verse poem with no prescribed rhyme or meter (metre in British English). The poem is an extended metaphor, with the author imagining the fog as a cat approaching on small, quiet steps, as cats do while stalking. The first line states that the fog "Came creeping down out of the north". This shows that it is a cold fog, coming from the northern part of America where there is often a lot of snow and ice during the winter time. The second line says that the fog "Gathered itself together", which means that it is getting thicker. In the third line, the poet uses the word "stately" to describe the way the fog moves. Stately means "having the appearance of authority or dignity"; it also means "majestic". The fog is majestic because it makes everything around it look mysterious and important. In the fourth line, the poet uses the word "nightmarish" to describe the fog. Nightmarish means "giving the impression of evil dreams or nightmares"; it also means "terrifying". The fog is terrifying because it can suddenly appear anywhere, even in places where there shouldn't be any fog - like at sea!