A sixteenth-century copy of a Byzantine diagram showing the basic astrological configurations of the planets: “Table of the whole circle of the 12 zodiac signs and how it is divided into aspects.” The table gives the degrees between the planets in each aspect, the symbol used to indicate that arrangement, and the distance in signs between planets in a given aspect.
Imagine looking down on the circle of the zodiac, the various aspects are illustrated in the following diagram.
This table of planetary aspects is in ms. Phill. 1553 in the Staatsbibliothek zu Berlin. Phill. 1553 is a sixteenth-century codex that includes various Greek mathematical texts by both classical and Byzantine authors, e.g., Ptolemy’s harmonics along with a commentary, excerpts from Ptolemy’s Syntaxis, and the common trio of astrolabe texts—Philoponus’s, Ammonious’s, and Gregoras’s (as well as a scholia on the last work).
More mechanically, the word σχηματισμούς translates as “configurations,” but here it means aspects, that geometric relationship that planets can have to each other. ↩
This diagram represents the geocentric cosmos, with the earth (γῆ) at the center, surrounded by spheres of the Moon (σελήν), Mercury (ἐρμῆς), Venus (ἀφροδίτη), the sun, Mars (ἄρης), Jupiter (ζεύς), and Saturn (κρόνος). An incomplete ring for the signs of the zodiac encircles the planetary spheres—only the symbol for Aries was added. Finally, the names of the zodiac were labeled in red on the outside, starting at 3 o’clock and proceeding counter clockwise:
Capricorn (αἰγώκερως (should be αἰγόκερως))
This diagram is part of a collection of astronomical diagrams in Royal MS 16 C XII, a latter 16th-century manuscript first owned by the brilliant classical scholar and historian Isaac Casaubon. Other texts in the in the codex all concern the construction and use of the astrolabe (the first text is a printed edition from 1544, the rest are manuscripts).
The ordering of the planets in this diagram poses a bit of a puzzle. As labeled, it suggests that the planetary order was: Moon, Mercury, Venus, Mars, [sun], Jupiter, Saturn. I’ve never come across that order before, i.e., Mars below the sun. What makes more sense is that the sun’s sphere, the fourth from the center, is instead labeled “ἄρης” because Mars’s sphere had been colored black (possibly before labeling any of them). Then, since writing wouldn’t show up on the black sphere, the person labeled Mars on the sphere below it, the sun’s. ↩
In 1498 Giorgio Valla published a Latin excerpt from Nicephorus Gregoras’s treatise “On the Construction and Origin of the Astrolabe.” Despite appearing as the fifth tract in Valla’s compendium, which included other Byzantine and Greek authors, Gregoras’s text quickly became a standard authority amongst scholars in 16th-century Europe. Authors such as Johannes Schöner and Peter Apian regularly cited him at various places in their own manuals on constructing and using astrolabes but do not appear to have read Gregoras’s text. Indeed, their familiarity with the Byzantine scholar seems to have been mediated through Valla’s excerpt.
This project has two parts. First, I am working on a critical edition and translation of Gregoras’s text. This volume will include a scholarly introduction that locates Gregoras and his work within the Byzantine tradition. The second part of the project explores how and why Gregoras became an authority for 16th-century Latin authors. This promises to illuminate how Byzantium came to occupy a place of intellectual and cultural importance in the sixteenth century, particularly amongst German scholars and humanists.
In March I am talking on the Byzantine polymath Nikephoros Gregoras and his efforts to establish his scientific authority. In “Empiricism, Prediction, and Instruments: The Creation of Expertise in 14th-Century Constantinople” I will examine the ways that Gregoras tried to distinguish his own expertise by grounding it in precise, empirical predictions and his command of technical knowledge.
This talk forms part of my larger project on Byzantine scientific knowledge. This larger project began from Gregoras’s text “On the Construction and Origin of the Astrolabe” (“Περὶ κατασκευαζῆς καὶ γενἐσεως ἀστρολάβου”).