At the turn of the century from 1480 to 1531 more than half a dozen different commintaries on Sacrobosco’s Sphera were printed yet among them all this one is arguably the most influential and important one, compiled by Francesco Capuano, (At some point he became known as Johannes Baptista Capuanus si Pontinus, de Manfredonia) Capuano was an author and professor of astronomy at Padua, Republic of Venice, then later became a bishop. This commentary was first printed in 1495 and was reprinted six times, up through 1531.

“In 1499, while Copernicus studies in Bologna, the commentary on Sacrobosco’s Sphere by the Padua master Francesco Capuano da Manfredonia first appears in print. It will be revised and reprinted several times thereafter. Like Copernicus, Capuano has a high view of astronomy and mingles astronomical and physical considerations (flies moving on wheels, men on ships, impetus, comets, raptus). Also, Capuano offers a flawed argument against a two-fold (diurnal and zodiacal) motion of the Earth.

Multiple thematic resonances between Capuano’s commentary and De revolutionibus, I, 5-11, suggest the hypothesis that Copernicus is answering Capuano, whose work was owned by Joachim Rheticus, if not Copernicus himself.”1 The authors who Capuano choses gives us a good picture of the state of teaching Astronom in the late 15th century.”

[Shank, Michael H. “Setting up Copernicus? Astronomy and Natural Philosophy in Giambattista Capuano Da Manfredonia’s ‘Expositio’ on the ‘Sphere.’” Early Science and Medicine, vol. 14, no. 1/3, 2009, pp. 290–315.  Evidence and Interpretation: Studies on Early Science and Medicine in Honor of John E. Murdoch (2009)JSTOR,

Capuano’s compelation adds a different selection of commentators and sources than other editions. Here are the Authors:

Michael Scott; 1175? -1234?
Petrus de Alliaco. (Pierre d’Ailly);1350-1420
Robertus Linconiensis. (Grosseteste); 1175-1253
Joannes Regiomontanus, 1436-1476.
Cecco d’Ascoli. 1269-1327, ; In spheram enarratio.
Jacques Lefèvre d’Etaples; d.1536. ; In astronomicum introductorium Ioannis de Sacrobosco commentarius.
Theodosius de Tripoli.( Θεοδόσιος); 160 B –100 BC; De spheris cum textu.
Johannes Cremonensis. 1114 – 1187; Theorica planetarum.

310J    JOHANNES de SACRO BOSCO fl1230
(Francesco Capuano Di Manfredonia fl 15th century)

Sphera mundi nouit[er] recognita : cu[m] co[m]me[n]tarijs [et] authorib[us] in hoc volumine co[n]te[n]tis vz Capuano, Giovanni Battista Cichi Eschulani cum textu. Ioannis Baptiste Capuani. Jacobi Fabri Stapulensis. Theodosii de spheris cum textu. Michaelis Scoti questiones. Petri de Aliaco cardinalis q[uaesti]ones. Roberti Linconiensis Compendium. Theodosij iterum de spheris cum textu. Tractatus de sphera solida. Theorice planetarum conclusiones cum expositione. Campani Tractatus de sphera. Eiusdem tractatus de computo maiori. Joannis de monte regio in cremone[n]sem disputatio. Theorice textus cu[m] Joa[n]nis Baptiste Capuani exp[ositi]one. Ptolomeus De speculis. Theorica planetarum Joannis Cremonensis, plurimum faciens ad disputationem ioannis de monte regio, qua[m] in aliis hactenus i[m]pressis non reperies.

Venetijs: Luce antonij de giu[n]ta …,1518.              $7,000

IMG_1970Folio. Inches. A6, B-z8, Aa-Ff8, Gg6.
IMG_1968This copy is bound in full contemporary vellum.
Inner joints have been repaired there is worm tracks at the fold, the free endpaper has an ownership mark of the old hand. There is water staining throughout,but hardly browned.

Houzeau / Lancaster I, 1642. EDIT 16 CNCE 29259. STC 597. Essling 1975. – Not in Adams.

1) Shank, Michael H. (2009), “Setting up Copernicus? Astronomy and Natural Philosophy in Giambattista Capuano da Manfredonia’s Expositio on the Sphere”, Early Science and Medicine, 14 (1–3): 290–315, doi:10.1163/157338209X425597
2) Boner, Patrick J. (2010), Change and Continuity in Early Modern Cosmology, Archimedes Series, 27, Springer, p. 14, ISBN 94-007-0036-9

3) L Thorndike, The Sphere of Sacrobosco and its Commentators (Chicago, 1949).

“As I illustrate below in preliminary fashion, Capuano’s Expositio of the Sphere is considerably more significant, both on its own terms and in relation to Copernicus, than the modest earlier scholarship on him has realized.6 It reveals a late-fifteenth-century university master grappling with the motions of the Earth and their physical IMG_1974consequences, freely mingling natural philosophical arguments with
the astronomical material he was teaching. While commenting on Sacrobosco’s elementary text of the mathematics curriculum, Capuano also brings together salient arguments from the Physics and De caelo commentaries of the previous century, including the possibility of mixed circular motions and of combined rectilinear and circular motions. When Capuano examines hypothetically the arguments
for the motions of the Earth, he of course discusses its rotation, a familiar hypothesis in fourteenth-century natural philosophy. Surprisingly, he also attempts to refute a hypothetical two-fold motion of the Earth. Although Capuano defends the Earth’s immobility, his commentary significantly enriches our understanding of aca demic discussions of astronomy at the time of Copernicus.

The number, quality, and spec ificity of these resonances suggest the hypothesis that Capuano’s commentary on the Sphere may have served as a sparring partner for Copernicus, who is notoriously silent about his debts to con temporaries. These intriguing echoes are probably not coincidental, for this text is certainly connected to Copernicus’s circle, and prob ably to Copernicus himself.


An imperfect version of Capuano’s commentary on Sacrobosco
first appeared in a 1499 Venetian astronomical compendium, which also reprinted his Peuerbach commentary. His title in that edition suggests that he was still teaching at Padua as a layman. By the time Capuano had revised his commentary on the Sphere in 1505, he had become an Augustinian canon. In later editions, he men
tions a lunar eclipse of 15 August “in the current year of 1505,” which “we saw with all the associates and fathers” (36va).’3 This is evidently a reference to members of his order, to which he had introduced the mathematical sciences, teaching for at least twelve years, presumably in the Veneto.’4 The revised version of the com
mentary on the Sphere (with a new preface) did not appear until the astronomical compendium of 1508. At least two editions of both commentaries appeared in 1518 and two more in 1531. Capuano’s commentary on Sacrobosco was perhaps the longest of the genre until Christopher Clavius’s a century later.15

A Few Thematic and Dialectical Resonances between Capuano andCopernicus

Most of these issues show intriguing parallelisms to the front matter and the cosmological sections of Copernicus’s De revolutionibus,Book I. Most generally, the common outlook between Capuano and Copernicus is obvious. Like Regiomontanus, these two contem poraries see astronomy as a discipline at the apex of the sciences and one with physical consequences. They do not hesitate to use and to resolve, for their own purposes, arguments in natural philosophy. In addition, they both understand astronomy as causal.44 I now turn to some dialectical parallels between Capuano and Copernicus.

At one level, my suggestion that Copernicus appears to be answering Capuano is trivial. Since Copernicus argues against the set of all defenders of a central, stationary Earth, he is implicitly arguing against every member of the set, hence against Capuano.

As I hope to show, however, the issues that Capuano brings up inthis one treatise are IMG_1976sufficiently unusual, specific, and numerous to cast doubt on the hypothesis that the similarity is coincidental.  In De revolutionibus, I, after summarizing the main arguments for the centrality of the Earth and against its daily rotation (chap 44) Copernicus opens the manuscript of Book I with a reference to the “studies that deal with the godlike circular motions of the world” and lists among the topics in it

“the causes of the other phenomena of the heaven” (This passage was omitted in the 1543 edition); The Manuscript of Copernicus’ On the Revolutions: Facsimile, Complete ter 7), Copernicus in chapter 8 specifically takes on the arguments against the motion of the Earth. Instead of dealing piecemeal with the natural or unnatural character of such a rotation, he steps back to make a meta-point: if the Earth rotates, its motion is natural. Naturalness of motion will characterize whichever body is moving, whether the primum mobile or the Earth. Recall that one of Capua

no’s arguments for keeping the Earth stationary was that, if it moved, “there is no specifying that by which the Earth can move.” (33vb).Here, Copernicus’s appeal to its natural motion sounds like a direct answer to Capuano. In short, there is no independent criterion of natural motion, only a choice of options: either the heavens stand still and the Earth rotates, or the heavens rotate and the Earthstands still. In either case, the motion of the moving body and the immobility of the stationary one are natural; the question at hand is the determination of which body is in motion. In the process, Copernicus alludes to his own apocalyptic scenario if the heavensmove by raptus.45 Capuano had already rehearsed the arguments for the greater nobility of rest for the heavens and the greater ease of motion for the smaller body (the Earth), only to refute them. Copernicus adopted them.

Still in Chapter 8, Copernicus discusses the motion of comets (6r), and air. This passage caught the attention of Jamil Ragep, whowas puzzled by its apparent uniqueness in the Latin tradition.46 Significantly, Capuano had also discussed comets in the context of theraptus of the celestial spheres, not surprisingly perhaps, since the motion (or lack thereof) of the elements belongs to the problem of the motion (or lack thereof) of the Earth (30va). Copernicus uses raptus or its cognates three times in De revolutionibus I, 8

As we have seen, Capuano had argued that a sphere could move with mixed circular motion and elemental bodies could move with combined circular and straight motions. The availability of such arguments helps to explain Copernicus’s own appeal to mixed straight and circular motion (6r-v) and his rapid march through the tradi

tional natural philosophical problem of a rotating Earth in De revolutionibus I, 8. Although such arguments are scattered throughout fourteenth-century natural philosophy, we do not know precisely how they reached Copernicus. In Capuano’s revised commentary on the Sphere, they were not only readily available, but also put to work in a combined astronomical and physical context. Coperni cus put similar arguments to work for the elements, arguing that the apparent rectilinear rise and fall of the latter exhibit a compound of circular and rectilinear motion.47

IMG_1971But it is the matter of requiring more than one motion of the Earth that is most striking. In De revolutionibus I, 9, Copernicus’s argument resonates with the framework of Capuano’s discussion, which Copernicus has turned on its head. Having argued in De revolutionibus I, 8 that the mobility of the Earth is more probablethan its immobility, in the first sentence of Chapter 9, Copernicus asks, “whether several motions are appropriate for it” (7r).48 The immediate leap to the plural strikingly echoes Capuano’s argument rooted in De caelo, II, 14. After sketching his theory of gravity,49 Copernicus explores the consequences of making the Sun and Earth trade places and motions: “if the [yearly circuit] is transformed from solar into terrestrial, immobility being conceded to the Sun, the ris ings and settings of the zodiacal signs and the fixed stars, by which they become morning and evening stars, will appear in the same way.” On the force of this fundamental observational equivalence, Copernicus goes on to assert a stronger one:

“Also the stations, retrogressions, and progressions of the wandering stars will be seen to be not their own motion, but the Earth’s, which they transform into their appearances. Finally, the Sun itself will be thought to own the center of the universe….”50 These assertions are a direct denial of Capuano’s observational claim, which was probably rooted. in the objections of De caelo II, 14 and of Aquinas’s commentary on it, that the stars would exhibit “changes and turnings.”

If Copernicus had read the work, the incompatible premises in Capuano’s argument, generated by the juxtaposition of the simple motion of the fixed stars with the added assumption of “diurnal and zodiacal” motions, must have stood out when Copernicus tested. the consistency of his insight.

Strikingly, the passage in Capuano that immediately follows this discussion turns to the order of the planets, and discusses exten sively the place of Mercury and Venus in relation to the Sun: “Inthis question, it will be a matter first of the order of all the spheres;second, and more specifically, of the Sun, Venus, and Mercury.”5′

Precisely this problem, on Bernard Goldstein’s convincing interpre tation, motivated Copernicus’s move to heliocentrism by causing him to rethink the order of the planets-the subject of De revolutionibus I, ch. 1 0.52

Not least, Copernicus evidently agreed with Capuano that giving the Earth only diurnal and zodiacal motions could not save thephenomena. Accordingly, he spent the better part of De revolutionibus I, 1 1 offering two derivations of the third motion he ascribed to the Earth. Copernicus’s motion of “declination” keeps the Earth’saxis pointed in the same direction on an annual basis and also accounts for the precession of the equinoxes. Equally significant,immediately thereafter, the manuscript includes material omitted in the printed text, to the effect that Philolaus and Aristarchus probably saw the motions of the five planets as more consistent withthe mobility than the immobility of the earth “although they were not moved by the reason that Aristotle alleges and criticizes.”53 This
is a direct allusion to De caelo II, 14, the very passage that informsthe arguments of Aquinas and Capuano.

The significance of Capuano’s treatise lies less in the specific views he presents, many of which were scattered throughout late-medieval natural philosophy, than in his collection and linkage of them in a detailed commentary on the Sphere, the basic elementary text of the mathematical curriculum. In recasting Aristotle’s argument

against multiple motions of the Earth, Capuano called the two hypothetical motions “diurnal” and “zodiacal.” In so doing, he effec tively raised the possibility of the Earth’s being a planet-not sim ply a body rotating at the center of the universe, but a body with the traditional motions of the Sun. In Capuano’s commentary on the Sphere, written by a Paduan master whose path he may have crossed in Padua, Copernicus could conveniently find a range of recent and detailed arguments against the motion of the Earth. By1543, he had formulated arguments that look like answers tothem.

But was Copernicus answering Capuano? First, Copernicus very likely knew about Capuano through the controversy with Alessandro Achillini. His studies in Bologna (1496-1500) overlapped with Achillini’s tenure and publication of De orbibus (1498).54

A new piece of evidence increases the likelihood of his familiarity with Achillini’s work. De orbibus contains several mysterious citations from Averroes’s Epitome of the Almnagest, previously thought to be available only in Arabic and Hebrew.55 Equally intriguing, Copernicus cites this work, calling it Averroes in Ptolemaica paraphrasi, when discussing a possible transit of Mercury (De revolutionibus, 8v), the topic of one of Achillini’s quotations.56 Second, if Copernicus did not know about Capuano through Achillini in Bologna, he is likely to have heard about his commentaries (the commentary on Peuerbach competed with that of Brudzewo, who was probably Copernicus’steacher in Cracow). Ihird,

Copernicus and Capuano easily could have met: Copernicus’s years in Padua (1501-03) are bracketed by the years in which Capuano was publishing in the Veneto and presumably teaching his fellow canons there. Not least, Capuano’s Expositio of the Sphere was known in Copernicus’s circle. The Stockholm,Royal Library, copy of the 1518 Venice Giunta astronomical com pendium containing Capuano’s two works is inscribed to “loachimo Rhoetico.”57

L.A. Birkenmajer believed that Copernicus gave the volume to Rheticus (see his Stromata Copernicana (Cracow, 1924), 320-21); Andr? Goddu is skeptical (“Coperni cus’s Annotations: Revisions of Czartoryski’s ‘Copernicana,'” Scriptorium, 58 (2004),

202-226, 207-08). The volume (106A, Fol. RAR) contains annotations in several hands, at least one of which (Goddu’s Plate 39), in my view, strongly resembles Copernicus’s (166r).

[Shank, Michael H. “Setting up Copernicus? Astronomy and Natural Philosophy in Giambattista Capuano Da Manfredonia’s ‘Expositio’ on the ‘Sphere.’” Early Science and Medicine, vol. 14, no. 1/3, 2009, pp. 290–315.  Evidence and Interpretation: Studies on Early Science and Medicine in Honor of John E. Murdoch (2009)JSTOR,

Now to move almost two decades back.

 300J   JOHANNES de SACRO BOSCO. (c. 1195 – c. 1256) (also called John or Johannes Halifax, Holyfax, Holywalde, Sacroboscus, Sacrobuschus, de Sacro Bosco, or de Sacro Busto) And Georgius de Monteferrato

Figura sphere cu[m] glosis Georgii de Mo[n]teferrato artiu[m] [et] medici[n]e doctoris : gradiam [et] gloriam dabit dominus.

Venice [Jacobus Pentius, de Leuco] for Georgius de Monteferrato 1500, die 28 ianuarii. $11,000


(“The use of type 68G and of woodcut capitals in this book connect it with the latter part of 1500 and it is therefore taken to be dated ‘more veneto’ (BMC)
Quarto, 8 ½ X 5 ½ inches . 26 lvs, A-E4 F6 . There is a large woodcut on title page ‘sphera mundi’, see to the left and three other large woodcut diagrams in text. Woodcut capitals, also spaces with guide-letters. Tear repaired in corner of f. 2, with some text loss.

This copy is bound in full laced cased later vellum, blue edges,and recent marbled IMG_1981endpapers.  This is a illustrated incunable printed by Jacobus Pentius, de Leuce who started printing in 1495, his press was chiefly active after the turn of the century.
In 1220 Sacrobosco wrote Tractatus de Sphaera  in four chapters. The first chapter deals with the shape and place of the Earth within a spherical universe. The second chapter deals with various circles on the sky. The third chapter describes rising and setting of heavenly bodies from different geographical locations while the fourth chapter gives a brief introduction to Ptolemy’s theory of the planets and of eclipses.
This book, which predates Grosseteste’s astronomy book, is well written and was widely used throughout Europe from the middle of the 13th Century.
IMG_1983Sacrobosco’s De sphaera mundi was the most successful of several competing thirteenth-century textbooks on this topic. It was used in universities for hundreds of years and the manuscript copied many times before the invention of the printing press; hundreds of manuscript copies have survived. The first printed edition appeared in 1472 in Ferrara, and at least 84 editions were printed in the next two hundred years. The work was frequently supplemented with commentaries on the original text. The number of copies and commentaries reflects its importance as a university text.[4] de Sphaera, which was widely read and influential in Europe during the later medieval centuries as an introduction to astronomy. Though principally about the heavens it also contains a clear description of the Earth as a sphere, in the first chapter. “The Sphere” was required reading by students in all Western European universities for the next four centuries.

Goff J421; Klebs, A.C. Incunabula scientifica et medica,; entry 874.30; BMC V 566; HCR 14126; Essling 264; Sander 6668; Pell Ms 6718 (6683); Hillard 1153; Péligry 480; IGI 5353; Hubay(Augsburg) 1247; Pr 5705; GW M14661

United States of America. The Walters Art Museum Library
Library of Congress,New York Public Library,
Huntington Library, Smithsonian Institution, Univ. of Chicago, Williams College,

1. Owen Gingerich, Sacrobosco as a textbook. Journal for the History of Astronomy 19 (4) (1988), 269-273.
2. L Thorndike, The Sphere of Sacrobosco and its Commentators (Chicago, 1949).
3. J F Daly, Biography in Dictionary of Scientific Biography (New York 1970-1990).
4. Olaf Pedersen, “In Quest of Sacrobosco”, Journal for the History of Astronomy, 16 (1985): 175-221. Pedersen identifies 35 printings in Venice, another 35 in Paris, and more in 14 other cities throughout Europe.


Gassendi 1683_1
263J Gassendi, Pierre (1592-1655); Galilei, Galileo (1564-1642); Kepler, Johannes (1571-1630)

Petri Gassendi Institutio Astronomica: Juxta Hypotheseis tam Veterum quàm Recentiorum. Cui accesserunt Galilei Galilei Nuncius Sidereus; et Johannis Kepleri Dioptrice. Tertia editio prioribus Correctior.img_3894

London: Jacob Flesher for William Morden, 1653.                                             $22,000

Octavo: 18.3 x 11.8 cm. 3 parts in one volume: [16], 199, [1]; 173, [1] p., 4 leaves of plates. Collation: A-N8, O4; A-L8 (including the final blank leaf)

SECOND EDITION THUS, Fourth edition overall of Gassendi

IMG_0471A nice copy in contemporary, blind-ruled English calfskin, rebacked.    The first title page is printed in red and black. Galileo’s “Sidereus Nuncius” and Kepler’s “Dioptrice” are introduced by separate title pages.  The text is illustrated with astronomical woodcuts including images of the moon, showing its uneven, mountainous surface as discerned by Galileo through the telescope and four full-paged woodcut illustrations of stars (the Pleiades, Orion’s belt, the Praesepe and Orion Nebulas.)

Gassendi’s “Institutio Astronomica,” has been called the first modern astronomy textbook. It is divided into three sections: the first details the so-called theory of the spheres, the second describes astronomical theory, and the third discusses the conflicting ideas of Brahe and Copernicus. The present edition is important for the inclusion of two seminal works of telescopic astronomy: Galileo’s “Sidereus Nuncius” (first ed. Venice, 1610), in which announces his discovery of Jupiter’s moons, and Kepler’s “Dioptrice” (first ed. Augsburg, 1611), Kepler’s brilliant explanation of how the telescope works.Galileo’s Discoveries with the Telescope:”Galileo’s ‘Starry Messenger’ contains some of the most important discoveries in scientific literature. Learning in the summer of 1609 that a device for making distant objects seem close and magnified had been brought to Venice from Holland, Galileo soon constructed a spy-glass of his own which he demonstrated to the notables of the Venetian Republic, thus earning a large increase in his salary as professor of mathematics at Padua. Within a few months he had a good telescope, magnifying to 30 diameters, and was in full flood of astronomical observation.”Through his telescope Galileo saw the moon as a spherical, solid, mountainous body very like the earth- quite different from the crystalline sphere of conventional philosophy. He saw numberless stars hidden from the naked eye in the constellations and the Milky Way.


Above all, he discovered four new ‘planets’, the satellites of Jupiter that he called (in honor of his patrons at Florence) the Medicean stars. Thus Galileo initiated modern observational astronomy and announced himself as a Copernican. (Printing and the Mind of Man)img_0473

Kepler’s Explanation of the Telescope:”In order that the enormous possibilities harbored in the telescope could develop, it was necessary to clear up the theoretical laws by which it worked. And this achievement was reserved solely for Kepler. With the energy peculiar to him, inside of a few weeks, in the months of August and September of the same year, 1610, he composed a book tracing basically once and for all the laws governing the passage of light through lenses and systems of lenses. It is called ‘Dioptrice’, a word that Kepler himself coined and introduced into optics. […]”In problem 86 in which he shows ‘how with the help of two convex lenses visible objects can be made larger and distinct but inverted’ he develops the principle on which the astronomical telescope is based, the discovery of which is thus tied up with his name for all time. Further on follows the research into the double concave lens and the Galilean telescope in which a converging lens is used as objective and a diverging lens as eyepiece. By this suitable combination Kepler discovers the principle of today’s telescopic lens. Even this scanty account sows the epoch-making significance of the work. It is not an overstatement to call Kepler the father of modern optics because of it. (Max Caspar, “Kepler”, pp. 198-199) Kepler’s work is also the first to announce Galileo’s discovery that Venus has phases like the moon.

Wing G293; Cinti 155; Sotheran, I p. 75 (1476); cf. PMM 113 and Dibner, Heralds of Science, #7 (the 1610 edition)IMG_0772 2