Answer: the theme of alienation and dissatisfaction.
In this excerpt, one of the elements of modernist poetry that is present is that of alienation and dissatisfaction. Modernist poetry often dealt with these ideas, as they believed that technology and society were often in the way of our achieving true happiness. In this poem, Richard Cory seems to have it all, and is admired by everyone. Nevertheless, he is unhappy enough to kill himself.
