At the time of writing, Kūkai was 24 years old. It is his debut work.
The text is three volumes in length. It is written in a dialectic style comparing and critiquing Confucianism, Taoism, and Buddhism. Teachers from each school of thought attempt to educate a dissolute nephew Tokaku. In volume one, Kibō lectures on Confucianism. In volume two, Kyobō Inji critiques Confucianism from a Taoism position. Finally, in volume three, Kamei Kotsuji critiques Taoism from a Buddhist position. The conclusion is that Buddhism is the superior philosophy.
The main characters appearing within the text were based on actual people:
- Kamei Kotsuji: Kūkai himself
- Tokaku: Saeki clan (佐伯氏?)
- Kibō: Ato no Ōtari (阿刀大足?)
- Kyobō: unclear but seems to be based on Sima Xiangru
- Kubota, Jun (2007). Iwanami Nihon Koten Bungaku Jiten (in Japanese). Iwanami Shoten. ISBN 978-4-00-080310-6.
- Nihon Koten Bungaku Daijiten: Kan'yakuban. Tōkyō: Iwanami Shoten. 1986. ISBN 4-00-080067-1.
- Watanabe, Shōkō; Yūshō Miyasaka (1965). Nihon Koten Bungaku Taikei: Sangō Shiiki, Shōryōshū (in Japanese). Iwanami Shoten. ISBN 4-00-060071-0.