Herzog is a portrait of an introspective, troubled hero. Saul Bellow has expressed his fear that the human species is losing its foothold on sanity and that the individual person is losing his capacity to comprehend ideas and to feel genuine emotions. Lacking necessary, justifiable ideologies, we are thrown back upon ourselves only to discover our own emptiness. Without moral certainty or without clear, rational explanations of the meaning of life, modern man is deeply troubled. Herzog is Bellow’s modern man, exploring the possibilities of the individual in contemporary society. Continually, he is assailed by neuroses and forces beyond his control, and he must struggle to maintain his identity and his humanity. It is this crisis of identity which is at the heart of Bellow’s novel.

What makes Herzog so overwhelming is its attempt to incorporate so many contrary ideas. Contrasted throughout the novel are nihilism and hope, despair and comic irony, alienation and accommodation. What Herzog is privately conflicts with the "mask" he wears in public; he is passive and masochistic, yet he tends also to be willful and sadistic. One of the novel’s major ideas is that people must survive by maintaining a painful awareness of this mixed human condition. Its hero also learns that it is impossible for one mind to comprehend all of human reality, and that the self is destroyed when it submits its destiny to others. Herzog is beset by "reality-instructors," those who try to determine his future and to fit him into their lifestyles. He must constantly struggle to assert his individuality. Finally, he discovers that existence involves the necessity of accepting fragmentation, flux, failure, suffering, irrationality, sexuality, decay, and death. The novel offers no answers beyond this recognition of our burdens and limitations. But, for Bellow, it is only through burdens and limitations that we can achieve identity.

Besides exploring humanity’s need for individuality, Bellow’s novel is also about the heart — indicated by the German herz in his hero’s name. The very fact that Herzog endures seems to belie his failure to grasp abstract reasons for survival. Herzog requires of each reader some sort of synthesis which only the private heart can achieve; it insists that each person must accept the burden of being human. This means conscious recognition of evil as well as goodness, failure as well as possibility, hate as well as love, limitation as well as freedom, and the importance of emotion as well as reason. Herzog refuses to surrender, to take "the easy way" and define himself with labels such as nihilist, romantic, sadist, or masochist. Life is not a system or a list of labels; life is more than mere facts and definitions. Life, Bellow shows us, involves realms of the heart that elude rational understanding.