The Convergence of Judaism and Islam. Religious, Scientific, and Cultural Dimensions

10

Al-Khwarizmi’s Mathematical Doctrines in

Ibn-Ezra’s Biblical Commentary

Michael Katz

In the introduction to his Hebrew translation of Ibn al-Muthanna’s Com-
mentary on the Astronomical Tables of al-Khwarizmi (780–845), Rabbi
Abraham Ibn-Ezra (1089–1164) writes:

... קם חכם גדול בישמעאל יודע סוד חכמת החשבון וחכמת

העתים... וזה החכם היה מחמד בן מוסי אלכואריזמי. וכל

חכמי הערבים שבימים האלה כופלים וחולקים ומוציאים

השורש ככתוב בספר החכם... והוא הוציא כל מעשה הלוחות

בדרך אחרת קלה על התלמידים שהיא שוה באחרונה

למעשה כנכה החכם מהאינדיאה רק לא נתן טעם לדברים.

[There arose a great scholar in Ishmael who knew the secret of the

wisdom of reckoning and the wisdom of times... and this scholar

was Muhammad ibn-Musa al-Khwarizmi. And all Arab scholars

nowadays multiply and divide and extract the root as is written in

the scholar’s book... and he brought out all the tables’ work in

another way, easy for the students, which is equal in the end to the

work of Kanka the Hindu scholar, but he gave no reason for the

words.]

Ibn-Ezra is best known as one of the leading biblical commentators in the
Judaic tradition. But in the wide spectrum of his writings we also find po-
etry, science, linguistics, philosophy, and mathematics. Specifically, math-
ematics is thoroughly and systematically studied in two books by Ibn-
Ezra—Sefer ha-Ehad (Book of the Unit) and Sefer ha-Mispar (Book of the