The Idan medical monograph was originally written by Yoshimasu Todo (1702-73). Tsuruta Gen'itsu (1727-56), Todo's student, edited the first version. And after his death, his fellow student, Nakanishi Shinsai (1724-1803), revised and expanded the work, publishing it in 1759. Nakanishi claimed that this was the pioneering medical treatise penned by Todo, argued that it represented Todo's “original teachings, ” with playing up its sensational character.
There years after this book was published, Hata Kozan (1721-1804) wrote Seki-idan, severely criticizing Todo and Tsuruta's Idan. It ignited a raging debate, which divided the Edo period medical community in two. One side upheld Todo's Tenmeisetsu theory, which argued that the human life span was decided by the gods, while the other side opposed this premise. Horie Dogen's Ben-idan, Tanaka Eishin's Ben-seki-idan, Obata Hakuei's Ben-idan-hyosetsu, and Kaya Kyoan's Zoku-idan were published during the middle of this deflate. Here, I focus on the Idan and Seki-idan debate, and place this debate in the larger context of Edo period medical history.