Saul Bellow was an American author who wrote many books, essays, and short stories, and won both the Pulitzer and Nobel Prizes for literature (Wikipedia). He had a significant influence on 20th century writing, and is widely read and studied today.
Because of his ethnic and multi-national upbringing, Bellow infused his works with themes of individualism, intellectualism, and honesty. He was critical of people who tried to force their world-view on others, calling them "reality instructors" and using them as antagonists in many of his books.
In Herzog, the main character is a partial antagonist himself, as he is deeply suspicious of intellectualism in others; however, he is also very susceptible to criticism and spends his time writing mental letters without real-world confrontation.
In Humboldt's Gift, protagonist Charlie's intellectual honesty is criticised by his former friend Humboldt, whose jealousy makes it impossible for him to be honest about Charlie, attributing his success to selling out instead of genuine talent. For his part, Charlie admires Humboldt's own talent, even as he is savaged in print; he is more concerned with the intellectual pursuit for its own sake, which also makes him vulnerable to a gangster who tries to piggyback on his success.
Other themes Bellow used often are: materialism, religion (specifically Judaism) in modern culture, mental instability, and the unconscious dishonesty of well-meaning people (Wikipedia).
More themes from Saul Bellows novels grow out of the commonalities shared between his protagonists. We can call these character themes:
- Sensitivity and philosophical/artistic sensibility as practical weakness.
- Using history (personal and world history) as a defense against the necessary choices of the present.
- A search for personal, individual truth and the difficulty in finding that truth in "the world".
- Intellectualism as sensitivity or sensibility (an awareness of the arts leads to an awareness of the movements of the mind, the references of the heart, etc.)
Then, to look more topically at narrative themes Bellow often explores you can look at:
- Family in general.
- One-sided love affairs and one-sided relationships.
- Success and the disappointing spiritual repercussions of professional success.