Abraham bar Ḥiyya ha-Nasi | |
|---|---|
אברהם בר חייא הנשיא | |
| Born | c. 1070 |
| Died | 1136 or 1145[1][2] |
| Known for | Quadratic equation Hebrew calendar |
| Scientific career | |
| Fields | Astronomy Mathematics |
Abraham bar Ḥiyya ha-Nasi[note 1] (Hebrew:ר׳ אַבְרָהָם בַּר חִיָּיא הַנָשִׂיא;c. 1070 – 1136 or 1145), also known asAbraham Savasorda,[note 2]Abraham Albargeloni, andAbraham Judaeus, was aCatalan Jewishmathematician,astronomer andphilosopher who resided inBarcelona, then in theCounty of Barcelona.
Bar Ḥiyya was active in translating the works ofIslamic science intoLatin and was likely the earliest to introducealgebra from theMuslim world intoChristian Europe. He also wrote several original works onmathematics,astronomy,Jewish philosophy,chronology, andsurveying. His most influential work is hisḤibbur ha-Meshiḥah ve-ha-Tishboret, translated in 1145 into Latin asLiber embadorum.[11] A Hebrew treatise onpractical geometry and algebra, the book contains the first known complete solution of thequadratic equation, and influenced the work ofFibonacci.[12]
Abraham bar Ḥiyya was the great-grandson ofHezekiah ben David, the lastGaon of theTalmudic academies in Babylonia. Bar Ḥiyya occupied a high position in the royal court, serving asminister 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 ofBanu Hud ofZaragoza-Lleida; there is even a record of a Jewish Savasorda there in the beginning of the 12th century. In his travelogues,Benjamin of Tudela mentions bar Ḥiyya living in Barcelona in the 1160s.[13]
According to Adolph Drechsler, bar Ḥiyya was a pupil ofMoshe ha-Darshan and teacher ofAbraham ibn Ezra. He was held in high consideration by the ruler he served on account of his astronomical knowledge and had disputes with learnedCatholic priests, to whom he demonstrated the accuracy of theJewish calendar. Abraham bar Hiyya is said to have been a great astronomer and wrote some works on astronomy and geography. One talks about the form of the earth, the elements, and the structure of the spheres.[14][7][15] Other works included papers on astrology, trigonometry, and music.
Some scholars think that the Magister Abraham who dictatedDe Astrolabio (probably atToulouse) toRudolf of Bruges (a work that the latter finished in 1143) was identical with Abraham bar Ḥiyya.[16] Although the title "Sephardi" is always appended to his name, Barcelona was at the time no longer under Muslim rule, and therefore not part of Sepharad. Abraham Albargeloni (i.e., from Barcelona) thus belonged to the community of theJews of Catalonia.
Catalonia joinedProvence in 1112 andAragon in 1137, and thus the County of Barcelona became the capital of a new Catalan-Aragonese confederation called theCrown of Aragon. The kings of Aragon extended their domains toOccitania in what is nowsouthern France. Abraham Albargeloni spent some time in Narbonne, where he composed some works for theHachmei Provence, in which he complained about the Provençal community's ignorance of mathematics.[4]
Abraham bar Ḥiyya was one of the most important figures in the scientific movement which made theJews of Provence, theJews of Catalonia,Spain, andItaly the intermediaries betweenArabic science and theChristian world, in both his original works and his translations.[4]
Bar Ḥiyya'sYesode ha-Tebunah u-Migdal ha-Emunah (Hebrew:יסודי התבונה ומגדל האמונה,lit. 'The Foundations of Understanding and the Tower of Faith'), usually referred to as theEncyclopedia, was the first European attempt to synthesize Greek and Arabic mathematics.[12] Likely written in the first quarter of the 12th century, the book is said to elaborate on the interdependence ofnumber theory,mathematical operations,business arithmetic,geometry,optics, andmusic.[17] The book draws from a number of Greek sources then available in Arabic, as well as the works of al-Khwarizmi andAl-Karaji.[12] Only a few short fragments of this work have been preserved.[4]
Bar Ḥiyya's most notable work is hisḤibbur ha-Meshiḥah ve-ha-Tishboret (Hebrew:חיבור המשיחה והתשבורת,lit. 'Treatise on Measurement and Calculation'), probably intended to be a part of the preceding work. This is the celebrated geometry translated in 1145 byPlato of Tivoli, under the titleLiber embadorum a Savasordo in hebraico compositus.[2]Fibonacci made the Latin translation of theḤibbūr the basis of hisPractica Geometriae, following it even to the sameness of some of the examples.[18]
Bar Ḥiyya also wrote two religious works in the field ofJudaism and theTanach:Hegyon ha-Nefesh ("Contemplation of the Soul") onrepentance, andMegillat ha-Megalleh ("Scroll of the Revealer") on the redemption of the Jewish people. The latter was partly translated into Latin in the 14th century under the titleLiber de redemptione Israhel.[2] Even these religious works contain scientific and philosophical speculation. HisMegillat ha-Megalleh was alsoastrological in nature, and drew a horoscope of favourable and unfavourable days. Bar Ḥiyya forecasted that theMessiah would appear inAM 5118 (1358 CE).[19][20]
Abraham bar Ḥiyya wrote all his works inHebrew, not inJudaeo-Arabic of the earlier Jewish scientific literature, which made him a pioneer in the use of the Hebrew language for scientific purposes.
Abraham bar Ḥiyya co-operated with a number of scholars in the translation of scientific works fromArabic intoLatin, most notablyPlato of Tivoli with their translation ofPtolemy'sTetrabiblos in 1138 atBarcelona.[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. Known translations of bar Ḥiyya include:
In the preface toẒurat ha-Areẓ, bar Ḥiyya modestly states that, because none of the scientific works such as those which exist in Arabic were accessible to his brethren in France, he felt called upon to compose books which, though containing no research of his own, would help to popularize knowledge among Hebrew readers. His Hebrew terminology, therefore, occasionally lacks the clearness and precision of later writers and translators.
Bar Ḥiyya was a pioneer in the field of philosophy: as shown byGuttmann in refutation ofDavid Kaufmann's assumption that theHegyon ha-Nefesh was originally written inArabic,[25][26] Abraham bar Ḥiyya had to wrestle with the difficulties of a language not yet adapted to philosophic terminology.
Whether composed especially for theTen Days of Repentance, as Rapoport and Rosin think, or not,[27] the object of the work was a practical, rather than a theoretical, one. It was to be a homily in four chapters on repentance based on theHafṭarot of theDay of Atonement andShabbat Shuvah. In it, he exhorts the reader to lead a life of purity and devotion. At the same time he does not hesitate to borrow ideas from non-Jewish philosophers, and he pays homage to the ancient Greek philosophers who, without knowledge of the Torah, arrived at certain fundamental truths regarding the beginning of things, though in an imperfect way, because both the end and the divine source of wisdom remained hidden to them.[28] In his opinion the non-Jew may attain to as high a degree of godliness as the Jew.[29]
He claimed that all gentile science had ultimately been learned by Jewish sages.[30]
Abraham bar Ḥiyya's philosophical system isneoplatonic like that ofSolomon ibn Gabirol and of the author ofTorot ha-Nefesh "Reflections on the Soul" asPlotinus 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. Both matter and form consist of two different elements. There is pure and there is impure matter. So also there is form too sublime to mingle with matter, such as that of the angelic or the upper world; and form which, being receptive and hollow, is susceptible to mixture with matter. The upper world, while gazing upon the lower and radiating its higher light, causes the mixture of matter with receptive form, the "tohu va-bohu"; and out of pure matter the celestial bodies, and out of impure matter the four elements, were evolved. But while the first formed into an inseparable combination and the mixture of the latter is one which constantly changes, a third form exists which mixes with matter for a certain time, to live again in a disembodied state after its separation, and this is the human soul. According to its wisdom—which makes it seek the upper world, the pure lasting form—or its folly—which makes it follow the impure matter of the perishable world below—the soul of man partakes of the nature of either the one or the other but, his destination being to live forever like the angels, man has been appointed by God to be the ruler of all beings on earth; and in the same measure in which he fulfills or deviates from his destination, does he rise or fall in dignity above or below his fellow creatures.[31]
He agrees withPlato that the soul in this world of flesh is imprisoned, while the animal soul craves for worldly pleasures, and experiences pain in foregoing them. 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.[32] But, precisely as man has been set apart among his fellow creatures as God's servant, soIsrael is separate from the nations,[33] the same three terms (bara,yaṣar, andasah) being used by the prophet for Israel's creation as for that of man inGenesis.[citation needed]
LikeBaḥya ibn Paquda,[34] 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 theHegyon ha-Nefesh,[35] though occasionally differing from it; but whileSaadia Gaon is elsewhere quoted by Abraham bar Ḥiyya, he never refers to him inHegyon.[36] Characteristic of the age is the fact that while Abraham bar Ḥiyya contended against every superstition, against thesuperstitions of the tequfoth,[37] against prayers for the dead,[38] and similar practises,[citation needed] he was, nevertheless, likeIbn Ezra, a firm believer inastrology. In hisMegillat ha-Megalleh he calculated from Scripture the exact time for the advent of the Messiah to be the year of the world 5118.[39] He wrote also a work on redemption, from whichIsaac Abravanel appropriated many ideas. It is in defense of Judaism against Christian arguments, and also discussesMuhammed "the Insane", announcing the downfall ofIslam, according to astrological calculation, for the year 4946 A.M.
Bar Ḥiyya'sḤibbur ha-meshīḥah ve-ha-tishboret contains the first appearance ofquadratic equations in the West.[11]
Bar Ḥiyya proved by themethod of indivisibles the following equation for any circle:, where is the surface area, is the circumference length and is radius.[40] The same proof appears in the commentary of theTosafists (12th century) on theBabylonian Talmud.[41]
This article incorporates text from a publication now in thepublic domain: Singer, Isidore; et al., eds. (1901–1906). "Abraham bar Ḥiyya ha-Nasi".The Jewish Encyclopedia. New York: Funk & Wagnalls.
This article incorporates text from a publication now in thepublic domain: Singer, Isidore; et al., eds. (1901–1906)."Abraham bar Hiyya ha-Nasi".The Jewish Encyclopedia. New York: Funk & Wagnalls. Sacerdote, G.; Guttmann, J.;Kohler, Kaufmann (1901–1906)."Abraham bar Ḥiyya ha-Nasi". InSinger, Isidore; et al. (eds.).The Jewish Encyclopedia. New York: Funk & Wagnalls.
{{cite book}}: CS1 maint: location missing publisher (link) One or more of the preceding sentences incorporates text from a publication now in thepublic domain: Singer, Isidore; et al., eds. (1901–1906). "ABRAHAM BAR ḤIYYA HA-NASI".The Jewish Encyclopedia. New York: Funk & Wagnalls.