Question XXXV. Does the Book of the Just exist? Or, how did it perish?

This Book of the Just does not exist, nor has it existed for a long time, as is clear from Theodoret (question 13) and other ancients. But [a book] of the same title, Sepher ha-Yashar, is found today, written by another — by Rabbenu Tam — in which [the matter] is treated learnedly, and not at all in a vulgar manner (Masius being the judge, in the catalogue of his Library), concerning the foundations and mysteries of divine worship. But how that [original Book] perished is uncertain — as Aben Ezra says concerning the Book of Wars, in Numbers 21. To Aben Ezra it seems to have perished, together with many others, through the injury of times and ages — especially since the Jews were so harassed by wars, captivities, and calamities, and dragged off to various shores. Of these [losses] the Rabbis indeed sometimes relate that even many sacred and canonical books, because they were judged less necessary, were burned by Ezra and the teachers of the same age, and other Prophets. But about this I have already treated elsewhere, in the Biblical Prolegomena.