The book’s primary biographical focus is on Ramanujan. Of humble origins, Ramanujan rose to become one of the foremost mathematicians of the 20th century. As a person, Ramanujan was highly regarded, and Kanigel often portrays him in this light. His life story coincides with World War I and the colonization of India by the British. The historical background that Kanigel provides helps place Ramanujan’s life in context and gives a fuller sense of the world Ramanujan existed in.

Ramanujan insisted that he obtained his mathematical gifts from divine sources, and he saw his insights almost as revelations from unknown and mysterious sources. His mother was influential in this regard, and his upbringing took place within traditional Hindu religious practice. He was a Brahmin, and in the Indian caste system, these were the people most likely to adhere strictly to religious fundamentals and tenets. Though he was supremely confident in his abilities and gifts, Ramanujan was also highly self-conscious. He loathed the idea that others would not see him as the genius he considered himself to be, and when he suffered a setback, he often responded dramatically. The book recounts a few notable occasions when Ramanujan, after suffering some kind of failure, disappeared for days at a time, and even once attempted suicide.