“Ptolemaeus Byzantinus”: The reception of Ptolemy’s astronomy in the Byzantine world

Persistent identifier: http://nrs.harvard.edu/urn-3:hlnc.essay:LempireJ.Ptolemaeus_Byzantinus.2018


My research aims to make an important contribution to the history of Greek astronomy through the study of manuscripts, following two complementary lines of research: on the one hand, the editing – together with translation and commentary – of Greek astronomical texts from Late Antiquity (5th-6th centuries) and the Byzantine period (7th-15th centuries); on the other hand, the identification and analysis of the milieus in which Byzantine astronomical manuscripts circulated. Such a study of the sources show that the practice of astronomy, far from being a niche intellectual pursuit, was very widespread in Greek culture and that Byzantium was in this field a real scientific crossroads between East and West. This project requires an ambitious but realistic study that will offer in the long term a broad treatment of Ptolemy’s astronomical corpus in the Greek language. This work follows on directly from current research on Ptolemy’s Handy Tables, a large set of tables which had a major influence on medieval astronomy, both Eastern and Western, and in the Renaissance.

The first part of my project involves studying the practice of Ptolemy’s astronomy and scientific education in Late Antiquity from a corpus of ancient scholia that attest to the transmission of astronomy during the 5th and 6th centuries in the Neoplatonic schools of Alexandria, Athens and the Near East (Syria). The second part, dealing with the reception of Ptolemy’s astronomy in the Palaeologan period (1261-1453), is divided into many related topics. As a CHS Research Fellow, I especially intended to prepare an edition – together with translation and commentary – of the treatise New Tables of the Byzantine monk Isaac Argyrus (1300/1310 – about 1375) whose scientific contribution to the Palaeologan period is a key element. This research on Greek astronomy during the brilliant Palaeologan period reflects the long-term history of the humanism of Hellenic civilization.

Research Progress

Greek manuscripts in the 14th and 15th centuries are evidence of an intense intellectual activity in Byzantium. Many learned figures – Theodore Metochites, Nicephorus Gregoras, Isaac Argyrus, Theodore Meliteniotes, John Chortasmenos, George Gemistus Plethon, Cardinal Bessarion – are associated with this prolific period and are relatively well known (intellectual profiles, works, writings in manuscripts). But their precise role in the teaching and transmission of astronomy remains poorly explained. In particular, it is difficult to assess the astronomical work of Isaac Argyrus (third quarter of 14th c.): there is no critical edition and, in the manuscripts, his original work is mixed with subsequent revisions and additions. There is also a scientific gap around the Jewish-influenced astronomical texts in 15th-century Byzantine manuscripts and the importation to Byzantium of Jewish astronomy.

Isaac Argyrus (1300/1310-ca 1375) is one of the leading figures in the renewal of traditional astronomy: his work falls within the movement of Byzantine adaptations of Ptolemy’s Handy Tables. He is a scholar whose personality, circle, and contribution to the discipline of astronomy are little known. To remedy this lack, I’m producing a critical edition of his treatise entitled New Tables. It is an adaptation of Ptolemy’s Handy Tables of the sun and moon (mean motions) and of Almagest tables of syzygies (that are the new and full moons), arranged for the Julian calendar (inclusion of the Julian leap year) and for the meridian of Constantinople (with the date of origin 1367 September 1). The edition of the New Tables (an unpublished treatise of around 15 folios in a dozen manuscripts) should serve to understand the precise methods of Argyrus’ work of revision of the ancient tables that Ptolemy had created in Alexandria. More generally, the study of the astronomy of Argyrus makes it possible to take stock of a number of controversial questions about his scientific contribution: the correction of the length of the tropical year, the revision of the paschal computus – which was the subject of lively controversy in this period –, and the use of tables of Persian origin.

As a CHS Research Fellow, I have studied three important manuscripts of Argyrus’ treatise On New Tables: Marcianus gr. 323 = M, Vaticanus gr. 208 = V, Vaticanus gr. 1059 = Va. These manuscripts are contemporary with the author and the oldest witnesses of the textual tradition. In addition, a part of the manuscript M is an autograph of Argyrus. The comparison (textual collation) between these three manuscripts, and my reconstruction of the original astronomical tables show that M is likely the closest manuscript to the original text. According to my analysis of the various lectiones of the three versions, V was copied on M, and Va on V. In the text about the tables of new and full moons for instance, V and Va contrast M with variations, notably omissions of titles, and Va present small omissions. An other example is found in the table of the 24-year periods (table of conjunctions): M values are correct except for the last line (51ˊˊ instead of 1ˊˊ expected); in V and Va, a mistake (+ 1 minute) already occurs in year 121 and repeats itself in subsequent periods. The early history of the text can also be deduced from my textual analysis: the Byzantine scholar John Chortasmenos (late 14th c.- early 15th c.), copist and owner of V and Va, who worked on Argyrus’ New Tables, used clearly the manuscript M, which seems to be copied by a student of Argyrus himself. This indicates the transmission path by which Chortasmenos employed the values of Argyrus’ tables for his calculation of the eclipse of the sun in the year 1409 (cf Caudano 2003).

My work on Argyrus’ New Tables should be extended to other manuscripts in order to provide a critical edition of the text and a detailed history. According to a first research, the other manuscripts of the treatise are the following witnesses:

Marcianus gr. 328 Vaticanus gr. 792
Monacensis gr. 100 Vaticanus gr. 1052
Oxoniensis Seldenianus 6 Vaticanus gr. 1411
Parisinus gr. 2400 Vindobonensis phil. gr. 160
Romanus Casanatensis gr. 484 Vindobonensis suppl. gr. 75
Scorialensis Ω.IV.15 (567)

Research on Isaac Argyrus reveals a link between his school and the Jewish communities of the end of the Byzantine world – in particular, the scholar Mordecai Comtino (1402-1482). Indeed, the event that most marked 15th-century Byzantine astronomy was the introduction of Jewish astronomical tables (see Tihon 2017). Little is yet known about Jewish influence on the Byzantine intellectual world at the end of the 14th century and in the 15th century and the topic has not been widely studied. Greek adaptations of three Jewish treatises – the Six Wings (Hexapterygon) of Immanuel Bonfils of Tarascon, the Cycles of Bonjorn, the Paved Way of Isaac ben Salomon ben Zaddiq Alhadib – raise some interesting questions about exchanges between Jewish communities and Byzantine intellectuals: how, and through whom, did the Byzantines come to know about Jewish astronomy? Did they come upon the Jewish treatises through Latin translations (the Jewish scholars whose works were adapted in Constantinople were all Jews originating from Provence or Spain)? Through which channels did these texts arrive in the Byzantine world? In terms of content, the Greek adaptations of the Jewish treatises highlight two major preoccupations of Byzantine astronomers at the time: calculating syzygies, associated with the problem of calculating the date of Easter, and predicting eclipses. From the linguistic point of view, these texts were completely adapted to the Greek language, and only the names of the months in the Hebrew calendar were transliterated. The study of a corpus of Greek manuscripts on this theme should allow a better understanding of this phenomenon of Judeo-Byzantine exchange. Three manuscripts that were widely circulated in the Byzantine world constitute the starting point of my investigation: Ambrosianus G 69 sup., Athous Vatopedi 188 and Parisinus gr. 2501. During my research at CHS, I paid special attention to the places where these witnesses were used and annoted – for example, we find some notes for Andrinople and Thessaloniki in the Ambrosianus – especially since these manuscripts present also some works of Isaac Argyrus.

Research Challenges and Impact

The Handy Tables of Ptolemy, whose conception of the universe was to prevail for some 1,500 years to come, constitutes an important resource for understanding the intellectual and scientific vitality of the Byzantine Renaissance as they have been copied, reworked, and adapted by many Byzantine scholars. My aim is to place the manuscripts in relation to the people: by means of a paleographical and codicological study of the various witnesses, I propose to rediscover the autograph manuscripts of these scholars, and to establish their milieu, their contribution and their influence. The cultural issue at the heart of my work is to showing that the Byzantine astronomers were open to the outside world (Arab-Persian culture, Latin West, Jewish communities) and, as a result of this, played a major role in the preparation of the European Renaissance. It is a vast cultural challenge that I put at the intersection of several disciplines: the history of science, the history of Byzantium, the Middle Ages and the Renaissance, the study of the Greek language and of Greek manuscripts, the edition of unpublished texts.

My research entails developing shared expertise with a number of colleagues working in various research teams abroad, in particular: the international project Ptolemaeus Arabus et Latinus (dir. Dag Hasse) hosted by the Bavarian Academy of Sciences and Humanities (Munich), and the ERC project Shaping a European Scientific Scene: Alfonsine Astro­nomy (2017­-2022, dir. M. Husson) at the Observatoire de Paris. In full accordance with these projects, my intention is to offer a long-term processing of the astronomical corpus in Greek language. There is a natural fit with these projects that is highly promising in terms of results given that our interconnected research projects on the reception of Ptolemy complement each other and lend themselves to investigation of an intercultural nature (Latin, Arabic and Greek).

Select Bibliography

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Bardi, A. 2018. “Bessarione a lezione di astronomia da Cortasmeno.” Byzantinische Zeitschrift 111:1-38.

Bydén, B. 2003. Theodore Metochites’ Stoicheiosis Astronomike and the Study of Natural Philosophy and Mathematics in Early Palaiologan Byzantium.

Caudano, A.-L. 2003. “Le calcul de l’éclipse de soleil du 15 avril 1409 à Constantinople par Jean Chortasménos.” Byzantion 73:211-245.

Constantinides, C.N. 1982. Higher Education in Byzantium in the Thirteenth and Early Fourteenth Centuries.

Lempire, J. 2016. Le commentaire astronomique aux « Tables Faciles » de Ptolémée attribué à Stéphanos d’Alexandrie. Tome I.

Mergiali, S. 1996. L’Enseignement et les lettrés pendant l’époque des paléologues: 1261-1453.

Mondrain, B. 2007. “Les écritures dans les manuscrits byzantins du XIVe siècle.” RSBN, N.S., 44:157-196.

Pingree, D. 1998. “Some Fourteenth-century Byzantine astronomical texts.” Journal for the History of Astronomy 29:103-108.

Tihon, A. 2008. “Numeracy and Science.” The Oxford Handbook of Byzantine Studies, 803-819.

———. 2009. “Les sciences exactes à Byzance.” Byzantion 79:380-434.

———. 2015. “Les astronomes byzantins entre Orient et Occident.” Byzantium as Bridge between West and East, 283-290.

———. 2017. “Astronomie juive à Byzance.” Byzantion 87:323-347.

Tihon, A., and R. Mercier. 2011. Πτολεμαίου Πρόχειροι Κανόνες. Ptolemy’s Handy Tables, vol.1a-1b.