Reuven is an intellectually curious, observant Jewish teenager living in Brooklyn with his father. He aspires to become a rabbi, possessing a strong aptitude for mathematics and Talmudic study. He experiences a shift in his worldview after a severe eye injury forces him into an unlikely alliance with the boy who hurt him. He values open communication, contrasting strongly with the silence found in his new friend's home.

Danny is a brilliant Hasidic teenager with a photographic memory and an insatiable desire for secular knowledge. As the oldest son of his sect's leader, he is expected to inherit his father's position. He secretly reads non-religious literature at the public library, working to reconcile his rigid upbringing with his fascination for Freudian psychology.

Reb Saunders is the powerful, deeply devout tzaddik of a Russian Hasidic sect in Williamsburg. He survived brutal attacks in Russia before bringing his followers to America. He raises his brilliant eldest son using a strict traditional method of silence, speaking to him only during public religious study sessions.

David Malter is an Orthodox Jewish scholar and progressive intellectual living in Brooklyn. He writes critical articles on the Talmud and firmly supports the creation of a Jewish state in Palestine. He openly communicates with his son and quietly recommends secular books to the voraciously curious Danny Saunders at the public library.

Levi is Danny's younger brother, a frail boy with a chronic blood condition. Despite his physical weakness, he exhibits a fierce inner tenacity. His health is a subject of intense focus for his family, particularly as it relates to the line of succession for the Hasidic dynasty.

Mr. Galanter is the energetic gym teacher at Reuven's yeshiva who serves as the softball coach. He speaks almost entirely in war metaphors but privately carries the burden of being unable to serve in the actual military due to his physical limitations.

Tony Savo is a professional boxer in his thirties recovering from a severe eye injury. He provides a secular, cynical perspective in the hospital ward, frequently complaining about his fighting career while showing genuine warmth toward the boys in his room.

Billy is a young blind boy awaiting an experimental operation to restore his sight. He maintains a bright, innocent demeanor and frequently talks about his uncle who flies bombers in the war, demonstrating a cheerful detachment from the harsher realities of life.

Roger is Billy's devoted father, a man managing the dual challenges of his son's blindness and raising his family alone after his wife's death. He expresses deep gratitude to those who show kindness to his son during their hospital stay.

Davey is a backup player on Reuven's softball team who also wears glasses. He serves as an informant of sorts, explaining the aggressive reputation of Danny's team and later delivering the somber news of President Roosevelt's death to the student council.

Dov is a large, physically imposing Hasidic boy who plays on Danny's softball team. His father works as one of Reb Saunders's bodyguards, reflecting his tough, unyielding presence on the field and in his community.

Manya is the Malter family's loyal Russian housekeeper. She ensures Reuven and his father are well-fed and cared for, providing a steady domestic presence, especially during David Malter's periods of illness and exhaustive political work.

Rav Gershenson is an esteemed, meticulous Talmud professor at Hirsch College who is known for spending days analyzing a single passage. He deeply respects David Malter's scholarship and recognizes Reuven's exceptional ability to dissect complex religious texts.

Professor Appleman is the chairperson of the psychology department at Hirsch College who favors experimental psychology over psychoanalysis. He heavily critiques Freud's methodology, causing early friction with Danny before eventually winning his intellectual respect.

Dr. Snydman is a lighthearted but highly professional doctor who oversees Reuven's eye surgery. He provides crucial medical updates to David Malter about the risk of scar tissue forming over Reuven's pupil.

Mrs. Carpenter is a strict, attentive nurse who manages the ward where Reuven recovers. She maintains order by keeping Tony Savo's boxing antics in check so the younger patients can rest in a peaceful environment.

Mickey is a six-year-old boy who has spent a significant portion of his life in the hospital due to chronic stomach issues. He eagerly seeks out Tony Savo for playtime and entertainment to break up the monotony of hospital life.

Sidney is the shortstop on Reuven's yeshiva softball team. He voices open frustration toward the Hasidic team's aggressive tactics and harsh language during their heated match.

Schwartzie is the starting pitcher for Reuven's yeshiva softball team. He struggles against Danny's aggressive batting style, prompting Reuven to take over the pitcher's mound to stop the offensive onslaught.

Dr. Grossman is David Malter's physician, tasked with monitoring the scholar's fragile health. He makes regular house calls after David suffers from severe heart attacks induced by overwork and political activism.