Although it's difficult to point to any one reason, it is clear that Jerry represents the alienated individual (a central theme in modern writing, especially existentialist writing) confronting the establishment figure in the person of Peter. Jerry is unstable; life has not been good to himas typified by the run down neighborhood that he lives in. Peter, while not rich, represents the well established middle class which would prefer to sit on the bench and read rather than deal with the misfit Jerry. Since there are many absurdist elements in the play, it's difficult to identify any particular reason why Jerry is as he is. Jerry is part of the human situation, a part that cannot find a place for itself in a world that does not seem to care, who is "killed" by its indifference.