Jesuit Science After Galileo: The Cosmology of Gabriele Beati ∗ KERRY V. M AGRUDER Abstract. Gabriele Beati (1607–1673) taught mathematics at the Collegio Romano when in 1662 he pub- lished an introduction to astronomy, the Sphaera triplex. This little work contains an interesting cosmic section which is analyzed here as representing a fusion of Jesuit traditions in cosmology achieved by Giovanni Battista Riccioli (1598–1671). The cosmic section enumerates three heavens, depicts fluid plane- tary heavens, and expresses hexameral biblical idiom. Woodcut and engraved variants of the cosmic section offer a glimpse of Jesuit freedom to experiment with various cosmological systems (Capellan, Tychonic and semi-Tychonic). Analysis of this cosmic section suggests several conclusions for the inter- pretation of visual representations, science and biblical interpretation, the Scientific Revolution and Jesuit science after Galileo. Keywords. cosmic section, cosmology, Gabriele Beati, Giovanni Battista Riccioli, hexameral tradition, Jesuit science, science after Galileo, sphaera, the Scientific Revolution, Tycho Brahe, visual representation One snapshot of mid-17th-century Jesuit cosmology is captured in the Sphaera triplex (1662) of Gabriele Beati (1607–1673). Twenty years ago William B. Ashworth, Jr. called attention to a cosmic section Beati published in this work as a striking fold-out plate (Figure 1). Ashworth noted that this depiction of the planets moving through fluid heavens offers a splendid pictorial representation of the dissolution of the solid celestial spheres (Ashworth, 1987). This essay will show how Beati’s cosmic section, in two variations, represents the fusion of Jesuit traditions in cosmology achieved by Giovanni Battista Riccioli (1598–1671). The Sphaera triplex, organized in three books, is a small, introductory mathematical textbook, a late descendant of the sphaera and theorica traditions (Thorndike, 1949). The first book, sphaera artificialis, briefly explains the circles used in the sphaera tradition, such as the horizon, meridian, celestial equator, or zodiac. The second book, sphaera elementaris, briefly reviews topics pertaining to the meteorological or sub-lunar region, such as the sphericity and location of the Earth, and the magnitudes of the Earth and elemental regions. Here, for example, Beati argued from stellar parallax for the centrality and immobility of the Earth. The final book, sphaera caelestis, occupies nearly two-thirds ∗History of Science Collections, University of Oklahoma Libraries, 401 W. Brooks, BL 521 Norman, Oklahoma 73019, USA. E-mail: [email protected] CENTAURUS 2009: VOL. 51: PP. 189–212; doi:10.1111/j.1600-0498.2009.00148.x © 2009 John Wiley & Sons A/S 190 K. V. Magruder Fig. 1. Gabriel Beati, Sphaera triplex (1662). Engraved cosmic section, tipped-in fold-out plate. Courtesy Rare Book Collection, Linda Hall Library of Science, Engineering and Technology, Kansas City, Missouri. of the text with a survey of topics in astronomy and cosmology such as the substance of the heavens, the motion of the heavens, the order or system of the heavens, the sizes and distances of the Sun, Moon and stars, lunar and solar eclipses, the nature and movement of the planets and the nature of comets and novae. The cosmic section appears in this last and longest part of the work. Born in Bologna in 1607, Beati published his first book, a collection of sacred poetry, three years before he entered the Jesuit order (Beati, 1624). A short mathematical study appeared after his assignment to the Collegio Romano (Beati, 1644). When Beati pub- lished a four-volume quarto work on cosmology and meteorology, the title page announced that he was lecturing in philosophy in the Collegio Romano (Beati, 1650). The Sphaera triplex title page indicates that in 1662 he was then teaching mathematics (Beati, 1662). One year later he was lecturing in theology, according to the title-page of a two-volume work on ethics, which was issued in a second, posthumous edition in the 18th century (Beati, 1663). Beati died in Rome on April 6, 1673.1 Beati was an ordinary practitioner who made no discoveries and provoked no known controversies, either within or without his order. For that very reason his work affords an interesting glimpse into the cosmological discussions of this robust and determined © 2009 John Wiley & Sons A/S Cosmology of Gabriele Beati 191 community of 17th-century scholars. Beati’s position as a mathematics lecturer at the leading Jesuit university, however fleeting, makes him worthy of some attention, while the unremarkable character of his career suggests that the Sphaera triplex reflects typical views which were not controversial at mid-century among Jesuits in Rome. 1. The Cosmic Section In their edition of the Louvain Lectures (1570–1572) of Cardinal Robert Bellarmine (1542–1621), George Coyne and Ugo Baldini suggest that there were two traditions in early 17th-century Jesuit cosmology, one physical and the other mathematical (Bellarmine, 1984, p. 43). The first, a physical tradition of non-mathematical cosmology, derived from Bellarmine and became disseminated through the Louvain Lectures. In these lectures Bel- larmine spurned the conflicting hypotheses of the astronomers in favor of more reliable authorities, particularly patristic interpretations of the hexameron or first chapter of Gene- sis. Only three heavens were required, Bellarmine argued, to account for the evidence of the senses and the testimony of scripture. Additional heavens were merely the hypotheses of mathematicians. Bellarmine rejected the fundamental assumption that planetary mo- tions should be explained by combinations of the uniform circular motions of solid spheres and instead thought of the planets as moving through a fluid heaven, leaving unaddressed astronomers’ questions about the orbs and their motions (Bellarmine, 1984, p. 43). In contrast, the mathematical Jesuit tradition identified by Coyne and Baldini followed the assumptions and techniques taught in the Collegio Romano by Christoph Clavius (1538–1612). Clavius’ lifelong work established astronomy as a prominent area of study in the Jesuit curriculum. His commentary on the Sphere of Sacrobosco, published in numer- ous editions from 1570 through 1611, became one of the standard astronomical texts of its time. Clavius largely succeeded in his endeavor to integrate the Ptolemaic system with the teachings of the Church. Ironically, he was himself the last major Ptolemaic astronomer, experiencing the misfortune of living long enough to see the end of its viability (Lattis, 1994; Grant, 2003; Remmert, 2009). After Clavius, Jesuits often inclined toward the system of Tycho Brahe. In the second half of the 16th century, Paul Wittich had transformed the mathematical beauties of Coper- nicanism into geocentric systems, as Scripture and sense seemed to require. Yet Wittich did not question the solidity of the orbs. When measurements of the parallax of comets con- firmed their varying distances from the Sun, Tycho considered a geoheliocentric system. In order to produce an integrated model of all the planets in one system, Tycho saw that the orb of Mars would necessarily intersect the orb of the Sun, although this would contradict the existence of solid orbs. Instead of solid orbs, then, the heavens must be fluid. After corresponding with Christoph Rothman, Tycho hastened his system into print in 1588, dissolving the solid spheres (Brahe, 1588; Donahue, 1981; Gingerich and Westman, 1988; Goldstein and Barker, 1995). © 2009 John Wiley & Sons A/S 192 K. V. Magruder Giuseppe Biancani’s Sphaera mundi (1620) displaced Clavius’ commentary on the sphere in many Jesuit colleges, representing a shift from the Ptolemaic tradition to the Tychonic system. Biancani explained the Tychonic system at length, with its advantageous combination of mathematical elegance, a geocentric Earth and fluid heavens. The Coper- nican system was discussed more gingerly, for the De revolutionibus of Copernicus was suspended in 1616 until it could be corrected and the corrections were only issued in the same year as Biancani’s work. Nevertheless, Biancani’s Sphaera carefully explained the Copernican system, labeled simply as the Pythagorean view. With Ptolemy finally dead and buried, the Jesuits needed a new astronomy, a new Almagest, offered in mid-century by Riccioli, a student of Biancani (Dinis, 2003). In his Almagestum novum (1651) the two Jesuit traditions converged. Riccioli’s synthesis of the mathematical tradition of Clavius with the physical tradition of Bellarmine consisted of four major features representative of mid-century Jesuit cosmology: justifying cosmolog- ical assertions by means of hexameral evidence, that is, according to the text of the six days of creation as given in the first chapter of Genesis; holding the number of heav- ens to be three; rejecting solid planetary orbs in favor of fluid heavens; and experimen- tation with various Tychonic and semi-Tychonic systems. The first three characteristics describe Bellarmine and others in the physical tradition, the latter two apply to writers in the mathematical-astronomical tradition. The well-known frontispiece of Riccioli’s treatise reflects mid-17th century perceptions well, depicting three major systems of the world (Figure 2). The Ptolemaic system rests discarded in the lower right corner. It could be rejected but not forgotten, in deference to Clavius. While all-seeing Argus looks on, Urania weighs in a balance the two chief world systems which remain. Against