By the 10th century, the knowledge preserved and developed in the Arabic Orient had begun making its way via the Maghreb to Spain, from where, after being translated into Latin, it would be taken up by European scholars. Chief amongst the translators of the Arabic scientific works to Latin was the Italian Gerard of Cremona (1114-1187) who had moved to Toledo in order to learn Arabic and access the city’s libraries of Arabic books. By contrast, the Jewish scholars in Andalusia and the Maghreb, who were proficient in both Hebrew and Arabic, would have had little recourse to translations: Maimonides’ famous Guide for the Perplexed, his Commentary on the Mishna, and his Responsa were all initially composed in Judeo–Arabic (Arabic written in Hebrew script). But their coreligionists in Provence and elsewhere in Europe would need Hebrew versions of these works.
Samuel ibn Tibbon (1150-1230) and his son, Moses ibn Tibbon, who was born in Marseille circa 1190 and died in 1283, were two of the most prolific Hebrew translators of their time. It was Samuel ibn Tibbon who first translated Maimonides’ Guide for the Perplexed into Hebrew as well as several chapters from his Commentary on the Mishna. His son Moses ibn Tibbon, a physician and author in his own right, is best known for his many Hebrew translations of Arabic works on philosophy, medicine, astronomy, and mathematics, of which the translation of Abu Bakr al-Hassar's Kitāb al-Bayān is an example.
The texts of the Vatican and Christ Church manuscripts are essentially identical and appear to have been copied from the same source. Not only do their versions of ibn Tibbon’s translation match, but both include the same appendix to al-Hassar’s treatise comprising a further nine examples and exercises. Whether these were added to the translation by Moses ibn Tibbon himself or by some later copyist is unknown but they must have been present in the source from which the texts of both manuscripts were copied. Apart from the inevitable copyist errors, such differences as there are between the Vatican and Christ Church manuscripts relate only to their scripts (Italian and Provencal/Sefardic, respectively), the layout of the script, and the annotations and corrections (marginalia) added by the respective copyists or later readers. In fact, there are numerous instances of the same error occurring in both versions. To cite just one case, the text of worked example 42 on the multiplication of fractions in both the Christ Church (fol. 12v) and Vatican (fol. 28v) manuscripts reads “… two thirds of five and five sixths by five sevenths of …”; however, the symbolic representation in both versions has “… two thirds of five and five sixths by six sevenths of ….” The versions of this example in the Arabic Gotha (Suter 1901, p. 26) and Schoenberg (fol. 44v) manuscripts both have “six sevenths,” to which the answer given in all four texts corresponds.
Indeed, other than the nine examples appended to the two Hebrew manuscripts and allowing for the differences that will inevitably arise when a text is translated into a different language, there is an almost one to one correspondence between ibn Tibbon’s Hebrew text and the Arabic texts in the Gotha and Schoenberg manuscripts. Every topic and worked example in the latter texts appears at the corresponding point in ibn Tibbon’s Hebrew translation. Even al-Hassar’s Arabic exaltations and invocations to Allah are matched by similar Hebrew praises and calls to God (Karpinski, p. 50). The one significant exception is in the opening lines of the work where al-Hassar explains what motivated him to write it. In Suter’s translation, the reason he gives is
that it was after I came to the realisation that the basis of [all] the sciences and fine literature, is the science of numbers, [coming of course] after Allah and the divine entities … (Suter 1901, p. 13).
The corresponding passage in the Hebrew translation reads:
Behold, God placed in numbers a hint of how to attain knowledge of His Oneness and of the order of His Creation, and by which to know every sealed and cryptic thing (fol. 1r, both Vatican and Christ Church manuscripts).
In both the Arabic and Hebrew versions, al-Hassar adds that he composed the work to be “a guide to beginners and a reminder to practitioners” and that
everything I have compiled, described and explained in this book, derives from the teachings of the older scholars, which I have logically clarified and expanded upon.