Astrology | Science Journal

Planetary model

Al-Bitruji proposed a theory on planetary motion in which he wished to avoid both epicycles and eccentrics,^[2] and to account for the phenomena peculiar to the wandering stars, by compounding rotations of homocentric spheres. This was a modification of the system of planetary motion proposed by his predecessors, Ibn Bajjah (Avempace) and Ibn Tufail (Abubacer). He was unsuccessful in replacing Ptolemy‘s planetary model, as the numerical predictions of the planetary positions in his configuration were less accurate than those of the Ptolemaic model,^[3] because of the difficulty of mapping Ptolemy’s epicyclic model onto Aristotle‘s concentric spheres.

It was suggested based on the Latin translations that his system is an update and reformulation of that of Eudoxus of Cnidus combined with the motion of fixed stars developed by al-Zarqālī. However, it is not known whether the Andalusian cosmologists had access or knowledge of Eudoxus works.^[1]One original aspects of al-Biṭrūjī’s system is his proposal of a physical cause of celestial motions. He combines the idea of “impetus” (first proposed by John Philoponus) and the concept of shawq (“desire”), of Abū al‐Barakāt al‐Baghdādī, to explain how energy is transferred from a first mover placed in the 9th sphere to other spheres, explaining the other spheres’ variable speeds and different motions. He contradicts the Aristotelian idea that there is a specific kind of dynamics for each world, applying instead the same dynamics to the sublunar and the celestial worlds.^[1]

Works

Al-Bitruji wrote Kitāb al-Hayʾah (The book of theoretical astronomy/cosmology, Arabic, كتاب الهيئة), which presented criticism of Ptolomy’s Almagest from a physical point of view. It was well known in Europe between the 13th and the 16th centuries, and was regarded as a valid alternative to Ptolemy’s Almagest in scholastic circles.^[1]This work was translated into Latin by Michael Scot in 1217 as De motibus celorum ^[4] (first printed in Vienna in 1531). A Hebrew translation by Moses ibn Tibbon was done in 1259.^[1]There is also an anonymous treatise on tides (Escorial MS 1636, dated 1192) which contains material seemingly borrowed from al-Bitruji.^[1]

Abū Maʿshar, Jaʿfar ibn Muḥammad al-Balkhī (also known as al-Falakī or Ibn Balkhī, Latinized as Albumasar, Albusar, or Albuxar) (10 August 787 in Balkh, Khurasan – 9 March 886 in Wāsiṭ, Iraq),^[2] was a Persian astrologer, astronomer, and Islamic philosopher, thought to be the greatest astrologer of the Abbasid court in Baghdad.^[1] He was not a major innovator and as an astrologer he was not intellectually rigorous. Nevertheless, he wrote a number of practical manuals on astrology that profoundly influenced Muslim intellectual history and, through translations, that of western Europe and Byzantium

Life

Abū Ma‘shar lived in Baghdad. Early in his work as an academic he studied the hadith. It wasn’t until he was 47 yeas old that he started studying astrology.^[3]

Astrology and natural philosophy

He found influence in the work of Greek, Mesopotamian, Islamic and Persian scholars.^[3] Richard Lemay has argued that the writings of Albumasar were very likely the single most important original source of Aristotle‘s theories of nature for European scholars, starting a little before the middle of the 12th century.^[4]

It was not until later in the 12th century that the original books of Aristotle on nature began to become available in Latin. The works of Aristotle on logic had been known earlier, and Aristotle was generally recognized as “the master of logic.” But during the course of the 12th century, Aristotle was transformed into the “master of those who know,” and in particular a master of natural philosophy. It is notable that the work of Albumasar (or Balkhi), in question, is a treatise on astrology. Its Latin title is “Introductorium in Astronomiam”, a translation of the Arabic Kitab al-mudkhal al-kabir ila ‘ilm ahkam an-nujjum, written in Baghdad in the year 848 A.D. It was translated into Latin first by John of Seville in 1133, and again, less literally and abridged, by Herman of Carinthia in 1140 A.D. Amir Khusrav mentions that Abu Maʿshar came to Benaras (Varanasi) and studied astronomy there for ten years.^[5]

Works

His works on astronomy are not extant, but information can still be gleaned from summaries found in the works of later astronomers or from his astrology works.^[1]

Introductions to astrology

Kitāb al‐mudkhal al‐kabīr, an introduction to astrology which received many translations to Latin and Greek starting from the 11th-century. It had significant influence on Western philosophers, like Albert the Great.^[1]

Kitāb mukhtaṣar al‐mudkhal, an abridged version of the above, later translated to Latin by Adelard of Bath.^[1]

Historical astrology

Kitāb al‐milal wa‐ʾl‐duwal (“Book on religions and dynasties”), probably his most important work, commented on in the major works of Roger Bacon, Pierre d’Ailly, and Pico della Mirandola.^[1]

Fī dhikr ma tadullu ʿalayhi al‐ashkhāṣ al‐ʿulwiyya (“On the indications of the celestial objects”),

Kitāb al‐dalālāt ʿalā al‐ittiṣālāt wa‐qirānāt al‐kawākib (“Book of the indications of the planetary conjunctions”),

Kitāb al‐ulūf (“Book of thousands”), preserved only in summaries by Sijzī.^[1]

Kitāb taḥāwīl sinī al-‘ālam (Flowers of Abu Ma’shar), uses horoscopes to examine months and days of the year. It was a manual for astrologers. It was translated in the 12th century by John of Seville.^[3]

Genethlialogy

Kitāb taḥāwil sinī al‐mawālīd (“Book of the revolutions of the years of nativities”). translated into Greek in 1000, and from that translation into Latin in the 13th century.

Kitāb mawālīd al‐rijāl wa‐ʾl‐nisāʾ (“Book of nativities of men and women”), which was widely circulated in the Islamic world.^[1]

Books available in Latin and Greek translations

De magnis coniunctionibus, ed.-transl. K. Yamamoto, Ch. Burnett, Leiden, 2000, 2 vols. (Arabic & Latin text)
De revolutionibus nativitatum, ed. D. Pingree, Leipzig, 1968 (Greek text)
Liber florum Translated by James Herschel Holden in Five Medieval Astrologers (Tempe, Az.: A.F.A., Inc., 2008): 13-66.
Introductorium maius, ed. R. Lemay, Napoli, 1995–1996, 9 vols. (Arabic text & two Latin translations)
Ysagoga minor, ed.-transl. Ch. Burnett, K. Yamamoto, M. Yano, Leiden-New York, 1994 (Arabic & Latin text).^[2]