The source that popularized this pictorial maxim is a 17th-century carving over a door of the famous Tōshō-gū shrine in Nikkō, Japan. The carvings at Toshogu Shrine were carved by Hidari Jingoro, and believed to have incorporated Confucius’s Code of Conduct, using the monkey as a way to depict man’s life cycle. There are a total of eight panels, and the iconic three wise monkeys picture comes from panel 2. The philosophy, however, probably originally came to Japan with a Tendai–Buddhist legend, from China in the 8th century (Nara Period). It has been suggested that the figures represent the three dogmas of the so-called middle school of the sect.
In Chinese, a similar phrase exists in the Analects of Confucius from 2nd to 4th century B.C.: “Look not at what is contrary to propriety; listen not to what is contrary to propriety; speak not what is contrary to propriety; make no movement which is contrary to propriety” (非禮勿視，非禮勿聽，非禮勿言，非禮勿動). It may be that this phrase was shortened and simplified after it was brought into Japan.
It is through the Kōshin rite of folk religion that the most significant examples are presented. The Kōshin belief or practice is a Japanese folk religion with Chinese Taoism origins and ancient Shinto influence. It was founded by Tendai Buddhist monks in the late 10th century. A considerable number of stone monuments can be found all over the eastern part of Japan around Tokyo. During the later part of the Muromachi period, it was customary to display stone pillars depicting the three monkeys during the observance of Kōshin.
Though the teaching had nothing to do with monkeys, the concept of the three monkeys originated from a simple play on words. The saying in Japanese is mizaru, kikazaru, iwazaru (見ざる, 聞かざる, 言わざる?) “see not, hear not, speak not”, where the -zaru is a negative conjugation on the three verbs, matching zaru, the modified form of saru (猿?) “monkey” used in compounds. Thus the saying (which does not include any specific reference to “evil”) can also be interpreted as referring to three monkeys.
The shrine at Nikko is a Shinto shrine, and the monkey is an extremely important being in the Shinto religion.The monkey is believed to be the messenger of the Hie Shinto shrines, which also have connections with Tendai Buddhism. There are even important festivals that are celebrated during the year of the Monkey (occurring every twelve years) and a special festival is celebrated every sixteenth year of the Kōshin.
“The Three Mystic Apes” (Sambiki Saru) were described as “the attendants of Saruta Hito no Mikoto or Kōshin, the God of the Roads”. The Kōshin festival was held on the 60th day of the calendar. It has been suggested that during the Kōshin festival, according to old beliefs, one’s bad deeds might be reported to heaven “unless avoidance actions were taken…”. It has been theorized that the three Mystic Apes, Not Seeing, Hearing, or Speaking, may have been the “things that one has done wrong in the last 59 days”.
According to other accounts, the monkeys caused the Sanshi and Ten-Tei not to see, say or hear the bad deeds of a person. The Sanshi (三尸?) are the Three Corpses living in everyone’s body. The Sanshi keep track of the good deeds and particularly the bad deeds of the person they inhabit. Every 60 days, on the night called Kōshin-Machi (庚申待?), if the person sleeps, the Sanshi will leave the body and go to Ten-Tei (天帝?), the Heavenly God, to report about the deeds of that person. Ten-Tei will then decide to punish bad people, making them ill, shortening their time alive, and in extreme cases putting an end to their lives. Those believers of Kōshin who have reason to fear will try to stay awake during Kōshin nights. This is the only way to prevent the Sanshi from leaving their body and reporting to Ten-Tei.