Sugi’s (d.u.) thirty fascicles (kwŏn) of collation notes to the carving of the second koryŏ Buddhist canon, finished around 1247, are the only extant records detailing how East Asian Buddhist scholars in the premodern era went about the task of collating and editing multiple recensions of thousands of scriptures into a definitive canon. Despite their importance, these notes have received surprisingly little attention to date from the scholarly community. Sugi’s notes help to document the textual genealogies of the various East Asian canons and provide definitive proof that, in style and format, the second Koryŏ canon imitated both the Song Chinese Kaibao Tripitaka and first Koryŏ canons, but its readings followed more closely those found in the Khitan Liao canon. A careful analysis of Sugi’s editorial process reveals that he was far more facile and astute than Erasmus (1466–1536), who initiated the formal Western art of textual criticism more than two centuries later. Sugi qualifies as a sophisticated editor, who adhered to the most basic canons of internal evidence followed in modern textual criticism. This study concludes with a lengthy appendix summarizing all of Sugi’s seventy-six entries regarding the sixty-five different texts that are specifically analyzed in the collation notes.