Abstract: There has been uncertainty among previous researchers over whether the version of Jihe Yuanben with an epilogue by Han Yingbi (Version A) was printed as the first edition in 1607. In comparison, a different text of more than a thousand characters exists in the commentary on the 5th definition in the 6th book of the version of Jihe Yuanben from the First Collection of Writings on Heavenly Learning (Version B) printed in the early reign of Emperor Chongzhen, providing textual clues for solving the mystery. This paper compares commentaries on the 5th definition in the 6th book of both aforementioned versions printed in Ming Dynasty with their counterparts in the Latin versions by Clavius, the first print in 1574 as well as later enlarged editions, with the findings are as follows: this text of commentary in Version A corresponds to Clavius’ first printed Elements in its structure and details, while specific paragraphs in Version B, regarding the theory of component intermediate ratios, the method of conversion of ratios in mixed fractions to ratios in integral numbers, and the art of Jiexiang, originate from Clavius’ later enlarged editions, thereby providing convincing evidence that Version A was printed as the first edition in 1607.

Key Words: Version of Jihe Yuanben with an epilogue by Han; Version of Jihe Yuanben from First Collection of Writings on Heavenly Learning; Clavius’ Euclidis Elementorum Librorum XV