 Many of his critics, such as sociologist Robert Bierstedt, argue that his literature contains a pessimistic connotation and that he speaks through sermons in his writings.These critics claim that Ehrenfeld's literature presents a bleak future and tends to focus more on the negative aspects of society towards the environment.Yet, others insist that his work represents optimistic view points in that it depicts the capacity of humans to reverse the forewarned implications of humans' environmental actions.