Thomas Eliot works multiple themes in the poem, however in general, his usage of imagery mainly represents ageing and decay. In the lines "When the evening is spread out against the sky / Like a patient etherized upon a table", the phrases like "sawdust restaurants" and "cheap hotels," the yellow fog, and the afternoon "Asleep...tired... or it malingers", represent decay. The character's concerns about his hair and teeth which is mentioned in the lines "Combing the white hair of the waves blown back / When the wind blows the water white and black," show the problems about aging.
The Big Dipper is an asterism in the constellation Ursa Major (the Great Bear). One of the most familiar star shapes in the northern sky, it is a useful navigation tool. Asterisms are prominent groups of stars that form patterns but are smaller than, or even part of, a constellation.
