What is the theme in The Human Comedy by William Saroyan?

Selflessness is another theme in the story. Many of the characters' efforts at being less lonely are manifestations of the book's two secondary themes. The first explores the idea of selflessness, of giving without expectation of return, of acting out of compassion. Spangler's generosity towards the young man with the telegram, Mary and Bess's generosity towards the three soldiers, Big Chris's compassion towards the trapped Ulysses, Marcus' compassion towards Tobey - indeed, the compassion of the entire Macauley family towards Tobey - all are manifestations of this theme.