"The Man Who Knew Infinity" is a captivating biography of the life of Srinivasa Ramanujan, one of the greatest mathematicians of the 20th century. Born into a poor Brahmin family in South India, Ramanujan struggled throughout his life with the challenges of life and science. Despite his humble beginnings and lack of formal education, he managed to contact the influential mathematician G.H. Hardy, who recognized his extraordinary talent and invited him to Cambridge. There, during World War I, Ramanujan developed groundbreaking mathematical theories and left a lasting legacy. Author Robert Kanigel vividly portrays the cultural and historical contrasts between subtropical India and cold Cambridge. This biography is not only a tribute to Ramanujan's genius but also an invitation to a broad audience to discover the beauty of mathematics without requiring deep prior knowledge.