The protagonist of Herzog is a man going through his second divorce and an internal crisis. Moses Herzog is reevaluating his life, recalling the events in his past that shaped him, and trying to come to some kind of conclusion about his own life and the world around him. He was raised in the slums of Montreal. He has strong feelings for his Jewish background family, loving his parents and siblings despite his differences with them. Moses also loves his daughter and son. Moses writes an unusual number of letters, not only to friends, but to acquaintances, strangers, the famous, and the dead. These letters reveal Moses as a man of sentiment and intellect. He struggles because of the conflict between his intellect and his emotion.

Moses has suffered a great deal. He has been diagnosed as a "depressive," but he is often optimistic, and by the end of the novel seems to find happiness by accepting the contradictions and ambiguities that exist in himself and in the outside world. In part, Moses finds happiness by allowing himself to accept limitations. For example, he realizes that he must repress certain of his emotions, or risk being judged insane. Although Moses ends the novel happily, we are left wondering whether his happiness is permanent, or simply a finite upswing in a cycle of happiness and suffering.