Koshitsu (study books about ancient history) (古史通)

"Koshitsu" is a series of books authored by Hakuseki ARAI, which analyze ancient Japanese history. It comprises four books, which were written in 1716. From the books, it can be observed that Hakuseki tries to grasp the real and rational picture of ancient deities by regarding them as humans and carefully exploring documents from a historical perspective.

Outline
In the beginning of the books, Hokusai elucidates his basic attitude toward studying the Kojiki (Records of Ancient Matters) and the Nihonshoki (Chronicles of Japan). Hakuseki insists that as ancient books use the On-reading of Chinese characters, readers should understand the meanings and contents of texts by listening to the sound of letters.

The body comprises four books. Book I: In the beginning, it is declared that deities are humans, and Hakuseki proposes the unique opinion that Takamanohara (plain of high heaven) is identified with Hitachi Province. In the ensuing sections, kuni-umi (the birth of the land of Japan) and birth of deities are discussed, followed by episodes until the ejection of Susanoo (the storm god in Japanese Mythology).

Book II: From Myths of Takamagahara to Myths of Izumo, this book introduces episodes from Ama no Iwato (The cave of the sun god) to Okuninushi no mikoto (chief god of Izumo in southern Honshu Island, Japan, and the central character in the important cycle of myths set in that region).

Book III: This book discusses Tensonkorin (the descent to earth of the grandson of the sun goddess) and Kuniyuzuri (transfer of the land).

Book IV: This book reveals the roots of Emperor Jimmu.

Influence and value
Contemporary Confucian scholars such as Razan HAYASHI thought that the origin of Japanese people could be traced to the descendants of Count Tai, king of the state of Wu. Meanwhile, Shinto scholars such as Kanekata URABE, an author of Shaku Nihongi (annotated text of the Nihon Shoki), and Kanera ICHIJO thought that deities were the roots of everything in the universe, and that Takamanohara was located in the heavens. Hakuseki, on the contrary, insisted that Takamanohara was located in Taka County of Hitachi Province because the land where the God of Sun appeared was pronounced in On-Kun reading as Hitachi and because in the Kyujiki (ancient Japanese historical text), taka in Takamagahara was described as Country named Taka.

After Hakuseki's death, the books were sidelined for a while, but their approach to analyzing ritual services and mythologies not as religion but as actual human history was reevaluated. The books were collected in the library of Mito Domain, and had a large influence on Shundai DAZAI, Sadatake ISE, and Baien MIURA.

Linguistic validation

In later years, however, different opinions on ancient kana orthography were proposed by Norinaga MOTOORI.