After the prime of manhood, Atsutane started to devote himself to the art of divination, which is said to be a philosophy of China, and the study of the calendar since 1831 (aged around 56).
壮年期以後の篤胤は1831年（天保2年）56歳頃から暦日や支那の哲学とも云われる易学に関心が傾倒して行く。