Abraham bar Hiyya
Bar Ḥiyya was active in translating the works of Islamic science into Latin and was likely the earliest to introduce algebra from the Muslim world into Christian Europe.
[12] Abraham bar Ḥiyya was the great-grandson of Hezekiah ben David, the last Gaon of the Talmudic academies in Babylonia.
Bar Ḥiyya occupied a high position in the royal court, serving as minister of police, and bore the title of governor (Hebrew: נשיא, romanized: nasi, lit. 'prince').
Scholars assume that Bar Hiyya would have obtained this title in the court of Banu Hud of Zaragoza-Lleida; there is even a record of a Jewish Savasorda there in the beginning of the 12th century.
[13] According to Adolph Drechsler, bar Ḥiyya was a pupil of Moshe ha-Darshan and teacher of Abraham ibn Ezra.
He was held in high consideration by the ruler he served on account of his astronomical knowledge and had disputes with learned Catholic priests, to whom he demonstrated the accuracy of the Jewish calendar.
Abraham Albargeloni spent some time in Narbonne, where he composed some works for the Hachmei Provence, in which he complained about the Provençal community's ignorance of mathematics.
[4] Bar Ḥiyya's Yesode ha-Tebunah u-Migdal ha-Emunah (Hebrew: יסודי התבונה ומגדל האמונה, lit.
[12] Likely written in the first quarter of the 12th century, the book is said to elaborate on the interdependence of number theory, mathematical operations, business arithmetic, geometry, optics, and music.
[4] Bar Ḥiyya's most notable work is his Ḥibbur ha-Meshiḥah ve-ha-Tishboret (Hebrew: חיבור המשיחה והתשבורת, lit.
[18] Bar Ḥiyya also wrote two religious works in the field of Judaism and the Tanach: Hegyon ha-Nefesh ("Contemplation of the Soul") on repentance, and Megillat ha-Megalleh ("Scroll of the Revealer") on the redemption of the Jewish people.
[23] There remains doubt as to the particulars: a number of Jewish translators named Abraham existed during the 12th century, and it is not always possible to identify the one in question.
[29] Abraham bar Ḥiyya's philosophical system is neoplatonic like that of Solomon ibn Gabirol and of the author of Torot ha-Nefesh "Reflections on the Soul" as Plotinus stated: Matter, being void of all reality, requires form to give it existence.
Now the union of these two by the will of God, which brings them from a state of potentiality into one of actuality, is creation, time itself being simultaneously produced with the created things.
Still, only the sensual man requires corrections of the flesh to liberate the soul from its bondage; the truly pious need not, or rather should not, undergo fasting or other forms of asceticism except such as the law has prescribed.
[citation needed] Like Baḥya ibn Paquda,[33] Abraham bar Ḥiyya distinguishes three classes of pious men: In accordance with these three classes of servants of God, he finds the laws of the Torah to be divided into three groups: Guttmann has shown that Naḥmanides read and used the Hegyon ha-Nefesh,[34] though occasionally differing from it; but while Saadia Gaon is elsewhere quoted by Abraham bar Ḥiyya, he never refers to him in Hegyon.
It is in defense of Judaism against Christian arguments, and also discusses Muhammed "the Insane", announcing the downfall of Islam, according to astrological calculation, for the year 4946 A.M. Bar Ḥiyya's Ḥibbur ha-meshīḥah ve-ha-tishboret contains the first appearance of quadratic equations in the West.
