One of the key themes of modernism is the way that man is presented as suffering from a profound dis-ease with himself and with his place in the world. Often the protagonists of modernist literature are characters who are isolated from the world around them and even from themselves, and suffer extreme loneliness as a result.
If we think about this theme of alienation and loneliness in this marvellous poem, we can see how it is reflected in Prufrock's inability to communicate or relate to other people, especially where women are concerned. Note the way that he addresses himself in the first line of the poem as "us," indicating that he is so used to being alone and talking to himself as if he were a friend because he is so isolated from society. In addition, what stresses his intense loneliness is the way that he imagines what people think of him and is obsessed by how he appears to others and how his actions would be interpreted:
With a bald spot in the middle of my hair--
(They will say: "How his hair is growing thin!")
My morning coat, my collar mounting firmly to the chin,
My necktie rich and modest, but asserted by a simple pin--
(They will say: "But how his arms and legs are thin!")
Note the way that Prufrock is examining his own appearance so intently. His self-doubt and dis-ease can only be expressed by asking himself a series of questions, as he clearly does not have anybody else to ask. Prufrock clearly suffers from a terribly poor self-esteem, but in this compelling poem T. S. Eliot presents us with a picture of the archetypal modernist man, who is ill at ease both with society and himself.