From A Place for Everything, by Judith Flanders (Basic Books, 2020), Kindle pp. 81-83:
Arabic dictionaries also used nonalphabetical methods of organizing. The Mukhaṣṣaṣ, or The Categorized, by Ibn Sīda (d. 1066), was divided, as its title states, by subject or topic, beginning with human nature and continuing on to physiology, psychology, women, clothes, food, and weapons. Al-Khalīl Ibn Aḥmad (d. 791), in his Kitāb al-‘ain, The Book of [the Letter] ‘Ain, used sounds to organize his work: he listed entries in an order of his own, where each sound group was followed by subcategories based on how many consonants a word contained. …
These mainly nonalphabetical developments contrasted with the works of Hebrew scholars, who tended toward alphabetical order simultaneously with (and occasionally a little ahead of) their Christian contemporaries. At the end of the eleventh century, Nathan ben Jehiel (c. 1035–c. 1110) produced his Sefer ha’Arukh, The Set Book. Ben Jehiel, who had been born in Rome, spoke Arabic, Aramaic, Greek, Hebrew, Italian, Latin, Persian, and Syriac, and he drew on his knowledge of these languages to produce an alphabetically ordered book of root words occurring in rabbinic literature. It became one of the best-known dictionaries of its type—more than fifty copies survive—as well as being one of the first Hebrew books to be printed, in Rome sometime before 1472.
Many of these works, both in Arabic and Hebrew, and the scholarship that had produced them, became accessible to scholars in Western Europe for the first time as these languages began to be more widely translated into Latin. … That so many of these works returned to the West via Arabic was significant, for earlier Arab scholars had frequently added substantially to the originals, including details of their own work, which was far in advance of much of Western thought at the time.
The Western rediscovery of the classics had two results, one somewhat abstract, one concrete. More generally, the awareness of how many great works had been entirely unknown before the lifetimes of these new readers, and of how many more had been permanently lost, produced a sense that the current generation needed to ensure that this recaptured knowledge, as well as all the works produced under its influence, were preserved for future generations. Further, it created a drive to ensure that the details contained in all these new works could be found easily—in other words, readers wanted not merely to read the books, but to refer to them: they wanted search tools.
These recently translated manuscripts also brought to the West other elements that are crucial for our story. Educated European readers now became increasingly familiar with foreign alphabets. In Italy and France in particular, Hebrew had routinely been transliterated into the roman alphabet when manuscripts were copied; in the rest of Europe, the Greek alphabet had sometimes been used, but less and less as time went on. In Europe, apart from Spain, where Arabic was in common use, Arabic too had been almost always transliterated into the roman alphabet. By contrast, some in the British Isles were familiar with Old English runes, known as futhorc, or with the Irish writing system known as Ogham. Many more would have recognized, and used in conjunction with the roman alphabet, the Old English runic letters such as thorn (Þ, þ) and wynn (Ρ, ρ). For these reasons, “foreign”-looking letters were more familiar and less unnerving in the British Isles, and so Latin and Hebrew letters were both used, as they were from the ninth century in Germany, a regular destination for highly educated monks from Ireland and Britain.