Kien studied further into the art of divination ('ekigaku' in Japanese), and based on his own philological theory did he advance a 'Kaibutsu-ron' theory (literally, 'kai' means opening and 'butsu' means objects, the 'kai-butsu' referring to a method of grasping the meaning of a word by voicing it so as to understand an object via name) which interpreted a relationship between 'name' and 'object,' and published books annotating many basic literature for Confucianism (which literature was called 'Keisho'), the books including "Roshi" (Lao Tzu or Lao-tse or Lao·zi; literally "Master Lao"), "Soshi" (Zhuangzi or Chuang-tzu; literally "Master Zhuang"), "Resshi" (Liezi or Lièzĭ or Lieh Tzu; literally "Master Lie") and "Rongo" (Lunyu in Chinese or Analects in English, also known as the Analects of Confucius).
易学について研究を深め、独自の言語論により「名」と「物」との関係を解釈する開物論を唱え、「老子」「荘子」「列子」「論語」など多くの経書に対する注釈書を著した。