SFERA; A FIFTEENTH-CENTURY INTERPLANETARY
VOYAGE
NAOMI MILLER
Art History Department Boston University 725 Commonwealth Avenue Boston, MA 02215
ABSTRACT. La sfera, an early fifteenth-century cosmological poem, composed in Florence, proliferated in
Renaissance manuscripts. A compendium of astronomy and geography, La sfera fuses universal subject matter with
praises of the Lord. Combining features of an astrological tract and navigators’ guide, its verses constitute a primer
of technical data on celestial phenomena. Marginal illustrations cast planetary bodies as allegorical personifications,
drawn from Biblical and classical texts, to evoke the vault of heaven and perfect Euclidean forms. Seeking further
inspiration, the poem is related to the luxurious Este De sphaera, and works by Ptolemy, Sacrobosco and Dante.
I. Introduction
The purpose of this talk is threefold:
1) to introduce you to a Renaissance best-seller, albeit in a limited edition, when it first
appeared in the early 15th century.
2) to provide a view of astronomy which combines features of an astrological tract and a
navigator’s guide.
3) to determine if the view of the heavens in this work is governed by the Ptolemaic
revival, yet still tied to the mentality of an earlier age.
To begin, some elementary clarification is in order, namely, the fusion of astronomy and
astrology in the 15th century. Astronomy, often designated as “mathematical astrology, at
once analytic and scientific; [it is] the study of the universe beyond the earth by means of
observation and calculation.” Here we may refer to Ptolemy’s Almagest or Mathematical
Synthesis, wherein Ptolemy categorized 1022 stars in 48 constellations; this mathematical
description of the solar system, translated from the Arabic in the late 12th century, was only
printed in 1515). Astrology represents the study of positions and aspects of heavenly bodies,
with a view to predict their influence on the course of human affairs, Encouraged by
religious and mystical tendencies of neo-Platonism, it was subject to attacks by Renaissance
humanists, as witness that of Pico della Mirandola (Garin, 1983). From a graphic point of
view, it may be noted that as both disciplines become demythologized, they become less
challenging to the artist. Hence, the expansion of celestial exploration produces relatively
stock images of the heavens.
II. Contents
La sfera is a cosmological poem comprised of four books each containing 36 stanzas in
ottave rime. It proliferated in 15th-century manuscripts; over 150 known codices survive and
18 editions were published between 1482 and 1543. Two books were added to the 1514
edition, proof of La sfera’s continuing vitality in the 16th century. Then came neglect and it
was only reprinted in 1859, 1863, and 1865, all exceedingly rare editions today (Bertolini,
1982, 1983, 1988; Segatto, 1983; Viti, 1982).
Although ascribed to Florentine Gregorio (hereafter, Goro) Dati or to his brother
Leonardo, with a terminus ante quem of 1435, the year of Goro’s death, neither author nor
date are secure, though a date about 1410 is favored. Whereas the authorship of La sfera is
still uncertain, recent criticism usually gives the attribution to the more worldly Goro (author
of a “History of Florence”), based largely on the testimony of most manuscripts and sources.
It has been noted that “the poem expresses its much-traveled author’s interests in astronomy,
cosmography, meteorology, geography, and navigation,” as compared to Leonardo’s position
within the Dominican order (Bertolini, 1984; Gentile, 1992). Enhanced by marginal
illustrations, La sfera fuses this universal subject matter with praises of the Lord, at the same
time serving as a primer of technical data on mariners’ instruments and an introduction to the
properties of heavenly bodies. Combining features of an astrological tract and a portolan
chart (that is, a navigator’s guide to harbors along a coast, indicating distances), La sfera
belongs to a rare genre elated for medieval and Renaissance sea-charts (Olschki, 1937).
Fig. 1. “La bussola,” Dati, La sfera, Florence, Biblioteca Medicea Laurenziana, ms. xv century, Med. Pal. 90, c. 9v.
Fig. 2. T-O Map, from Isidore of Seville, De Astris Coeli, Florence, Biblioteca Medicea Laurenziana, ms. 13
century, Plut. 29.39, c. 19v.
Divided into four books, each containing 36 stanzas in ottave rime, La sfera consists of
two main parts. The first focuses on celestial and terrestrial spheres, astronomical and
astrological phenomena, cosmography and geophysics; and the second explores the physical
geography of the known world on the basis of portolans and extant maps. In the first three
books, derived largely from ancient and medieval sources—such as the Commentari in
Somnium Scipionis of Macrobius, the Historia Naturalis of Pliny, the De Architectura of
Vitruvius, and the manuscripts of Isidore of Seville, as well as the geographical works of
Strabo, Pomponius Mela, and Ptolemy—the illuminations are largely schematic. Born of a
Dantesque vision, they are comparable, too, to images of the cosmos in medieval
mappaemundi (Orr, 1913, 1969). Note too that the treatises cited above were only made
available in Latin versions during the Renaissance. For example, Ptolemy’s Geography was
translated from Greek to Latin in 1406, and Strabo’s more theoretical Geography was
completed by Guarino Veronese in 1458 (Casella, 1972). Hence, the latter tomes were
probably not known to Dati. Book IV of La sfera constitutes a navigation manual, with its
nautical maps and chorographic elements; accompanying the text in the marginalia, the cities
and topographical features are frequently shown in vignettes, some with important
monuments. Eleven maps usually follow citations in the text describing coastal features of
trading centers and sites renowned through Christian pilgrimages. Many areas herein
depicted—the Mediterranean coast of Africa, Syria, Asia Minor, Rhodes—were, prior to the
Crusades, emblematic of Muslim rule. In fact, towns and castles in these drawings often
display distinct Islamic characteristics.
But since our concern today is with the heavenly sphere rather than the earthly, we move
from geography to astronomy. In the early 15th century, the rediscovery of Ptolemy’s
Cosmography and its proliferation in manuscripts preceded the dissemination of his
Almagest, first translated from Arabic to Latin by Gerard of Cremona in the late 12th century
and hardly studied before the late 15th century.
Fig. 3. “Trinity,” Dati, La sfera, Florence, Biblioteca Medicea Laurenziana, ms. xv century, Ashb. 555, c. 1v.
Fig. 4. Menabuoi, Giusto de’, “Creation of the World,” fresco, c. 1376, Padua, Cathedral Baptistery.
Examining La sfera in greater detail, we observe that Book I begins and ends on a
spiritual note. Opening with a ritual invocation “To the Father, to the Son, to the Holy
Spirit,” it closes with an account of the soul, seeking the “true way” and rendering eternal
thanks to the Deity. Between, the author presents a description of the cosmos as known in
the late Middle Ages. Illustrations depict the heavens, the stars as navigators, the planetary
bodies, the poles, the zodiac and their signs, the temperaments, the sun and the moon, and
such celestial phenomena as eclipses, while the text cites their effects on human nature
(Soldati, 1906; Garzelli, 1985; Warburg, 1966; Seznec, 1953).
We note the allegorical interpretations of heavenly bodies, as well as the teleological
character of the poem. In Med. Pal. 89 (Florence, Biblioteca Laurenziana), planetary
divinities are rendered by Apollonio di Giovanni as anthropomorphic personifications; for
instance, Luna is represented as an adult cupid. Illustrations in editions of La sfera provide
further evidence for notices of planets appearing in the guise of human beings. Abby
Warburg discusses early sixteenth-century prints illustrating allegorical poetry, based on
older models, linking figures of the planets to representations of political power (for example,
the Sun as emperor, Jupiter as the Pope).
Fig. 5. “Planetary Divinities,” Dati, La sfera, Florence, Biblioteca Medicea Laurenziana, ms. xv century , Med. Pal.
89, c.3..
Fig. 6. Dante, “Paradiso,” Florence, Biblioteca. Medicea Laurenziana, ms. xiv century, Med. Pal. 74, c. 310.
But, despite the late medieval framework, there is an attempt to understand the reasons
whereby Nature governs. Note particularly octave I.34, where the closing lines stress the
independence of “the soul [free of passions] that follows its nature,” thus separating man’s
spiritual and corporeal beings. Constant reference is made to circles and spheres with an
apotheosis to the sun, “more noble than any other star,” the light that illumines, the symbol of
God (I.16). Biblical texts are frequently evoked, as in words citing times of famine and
plenty, war and peace (Eccles. I.33), in an allusion to the Trinity (I.16), and in references
similar to those found in medieval specula. For all its pious evocations and its Dante-like
cosmology, one detects signs of rationalism. Concern with perfect forms and the natural
order is proleptic of early Renaissance humanism, with roots in Plato’s Timaeus. The poem’s
very focus on the sphere, most perfect of Euclidean geometric forms, is allied to that body
representing the vault of heaven, and to the mathematical symbols through which God may
be understood (Witttkower, 1949). Compare the Hermetic texts—particularly that of Nicolas
of Cusa--which influenced Marsilio Ficino’s astrological philosophy: “God is the center of a
circle whose center is everywhere and whose circumference is nowhere.” (Wittkower, 1949;
Moore, 1982)
Book II opens with a paean to God as Creator, followed by a description of the four
elements tied to a concordance with the temperaments, namely, the constitution of the four
humors (phlegmatic, sanguine, choleric, and melancholic--II.28-32) that denote the human
species. Appropriate personifications depict their respective characteristics. Physical
phenomena include glosses on the seasons and times of day, and such meteorological
conditions as winds and snows, and the effects of external circumstances on sailing and
finding positions. Speculative and scientific inquiries (II.9) and attention to measure (II. 34)
are interspersed with passages declaiming the vanity of earthly things.
Like the earlier books, Book III is addressed to the Creator, but here we find a description
of the inhabited world, and a summary version of the art of navigation, with notices that
follow pertinent to both merchants and pirates. Aside from nautical maps and general sailing
instructions, there are descriptions of the navigable zones of the earth, as well as data on land
maneuvers in different straits.
Encyclopedic-type references are unassimilated and bear no evidence of new discoveries,
but they do include notes pertaining to the etymology of the Red Sea. While describing ports
and inland cities, more or less in accord with older accounts, an element of skepticism
appears, such as that regarding the existence of Paradise: “Famous in scripture, and few
agree…” (III.23) Instead of relying solely on ancient or medieval texts, it seems as if Dati
seeks a more logical explanation for the splendor of Eden. But this said, Dati’s work
predates Renaissance polemics on astrology. Unlike Petrarch, in Dati’s poem, man’s destiny
is still determined by the stars (Segatto, 1983). That Dati is more allied to the encyclopedic
and didactic tradition is apparent in comparing verses from La sfera to those in Latini’s
Trésor or Fazio degli Uberti’s Dittamondo. Parallels have been found between Dati’s work
and the latter in references to the heavenly bodies, which abound with similar structures and
contents—the elements, meteorological phenomena, the rotation of the planets, the zodiac—
the whole, a concept of a medieval universe. Unequivocal sources of La sfera appear in the
Dittamondo, considered the origin of itinerary poems, a genre in vogue in the fifteenth
century. Dati would also have recourse to Ristoro d’Arezzo’s Libro della composizione del
mondo (ca. 1282), deemed “the first vernacular attempt at a scientific explanation of the
world.” (Whitfield, 1960).
Dati’s sources, however, can hardly be pinpointed or isolated. Most intriguing perhaps is
the depiction of the Tower of Babel, begun by Nimrod after the flood (III.26). Emphasizing
human pride and foolishness, the Tower inspired a multitude of interpretations; in Dante’s
Commedia, they range from towers marking the entrance to the City of Dis (Inf. IX—“…to
that high tower with the glowing summit…three infernal furies”), and the castle with seven
towering walls (Inf. IV), to Dante and Virgil observing Nimrod before the Tower of Babel
(Purg. XII). Its very presence should be noted in Giovanni Villani’s Cronica (1276?-1328),
one of the predecessors of Dati’s Istoria. Manuscript illustrations often recall contemporary
drawings of the Tower of Winds in ancient Athens (Brieger, Meiss, Singleton, 1969;
Huelsen, 1910). Actually, the latter octagonal marble monument, described by Varro and
Vitruvius as the Horologion of Andronikos, displayed a personification of a wind on each
side and functional devices as weather vane, sun dials, and water clocks—all features which
would have appealed to Dati’s navigational concerns.
Fifteenth-century contexts
Examining the contexts, we question the connection of La sfera to other cosmological
treatises , such as Sacrobosco’s De Sphaera Mundi (ca. 1233), a standard text on astronomy
and cosmography. Many manuscripts survive and incunabula editions follow the editor
princeps of 1472, This treatise has been said to have been “slavishly copied [from] an
elementary Arabic treatise” (Kuhn, 1957), but it is largely based on Greek science,
specifically, Ptolemy’s Almagest, wherein the circular world map is divided into five zones.
Another comparable work is the most seductive fifteenth-century De sphaera estense
(Modena, Bibl. Estense Lat. 209), whose miniatures represent planets and their offspring.
Although the style is retardataire in terms of the rendering of space, the pictorial details are
ravishing.
Fig. 7. “Earth surrounded by four elements.” Dati, La sfera, Florence, Biblioteca Medicea Laurenziana, ms. Med.
Palat. 89, c. 7v.
Fig. 8. “The Sun, with Leo and athletic and military games,” De sphaera, Modena: Biblioteca Estense ms., xv
century, ms. Lat. 209, c. 8v
Moreover, the iconography is redolent of a late medieval, even northern sensibility -- for
example, Venus is depicted with musical instruments in a manner akin to illustrations in the
Roman de la Rose; similarities are detected too in the Burgundian costumes and in
contemporary northern “ars nova,” the new music (Samek-Ludovici, 1958; Trottein, 1993).
This luxurious manuscript , ca. the mid-1460s was made for Francesco Sforza. Compare too
such cartographic works as Francesco Berlinghieri’s metric version of Ptolemy’s
Cosmography, the Geografia in terza rima, written in Florence, ca. 1480 (Auzzas, 1973).
With his focus on the sphere, comprised of the earth surrounded by ocean, Dati remains
Aristotelian and scholastic in his outlook, relying primarily on ancient and medieval
authorities.
III. Purposes
Finally, how may we determine the ways in which this work was used? Why was this
short poem so popular in the quattrocento? Who was the intended audience for these
manuscripts of La sfera, especially the more sumptuous ones, and what was their particular
appeal as gifts? Was the main function of this metric cosmography cum geography
didactic—an aide-memoire for seamen, amateur explorers, students, and dilettantes?
(Campbell, 1987) For example, are the maps herein drawn direct copies of portolans or
modifications of ancient maps used for their compilation? In other words, is La sfera a later
type of medieval portolan, indicating the expanding world of commerce in the early
quattrocento, at the same time retaining the sites known to earlier Christian pilgrims and
Crusaders?
Not surprisingly, the most luxurious manuscripts bear inscriptions of their original
destiny as presentation volumes, such as the one given by Leonardo Dati to a member of the
Florentine Bardis (BL: Add. Mss. 24,942) (Taylor,1931). Most of the surviving codices are
well-preserved; hence, we may assume that they were copies used for gifts, for study by
mariners far from sea, or for armchair travelers, rather than for shipboard use. Some authors
(Grafton & Rice, 1994) assert that “Dati used both learned and practical sources in this Italian
verse handbook on the sphere, which offered its readers—presumably boys learning to be
merchants—a lucid outline of traditional cosmology and geography and a very precise
description of travel in North Africa.” Nordenskïold, focusing on the geographical data,
views the poem primarily as a semi-popular work for navigators, explaining basic functions
and pointing out particular routes (Nordenskïold, 1889). Others (Soldati, 1906) view the
poem as essentially religious, in a Tuscan ottava rima that would be familiar to those versed
in the theological ideas of Dante. For example, Dati allegorically interprets the principal
celestial bodies as signifying attributes of God. Consider the union of three distinct
elements—body, heat, and light generated at the same moment, all emanating from the Sun,
most beautiful and worthy of God’s creations—and the significance of the divine Trinity.
Further, the rubrics before each verse—or series of verses—reveal an attempt at clarification
of the work’s cosmology, which represents a time of transition between the medieval and
modern worlds.
IV. Conclusion
At the beginning of this study, the attribution of authorship was not a primary
consideration. Some authorities state that La sfera was written in Latin by Leonardo and
translated into Italian by Goro. However, it seems that the very meaning of the manuscript is
tied to Goro Dati, its probable author. Leonardo (1365-1425), his brother, general of the
Dominican Order at Santa Maria Novella (where he lies in a tomb designed by Ghiberti), was
a Biblical scholar and participated at the Council of Constance. Despite the moral and
religious tones of La sfera, it is unlikely that a learned prelate would be capable of writing its
derivative and commonplace verses. Arguing for Goro’s (1362-1435) authorship, he was a
paradigm of the vita activa. A prominent silk merchant, he held many civic posts: eleven
times from 1362 to 1435 he was Consul of the Silk Guild; he was a political official in the
Florentine government as a member of the Dieci della liberta’, and standard-bearer of justice
in 1428-29. Hence, he emerges as the likely author of a volume, tied to the pseudo-scientific
atmosphere of the early Renaissance.
La sfera must be studied, too, in the context of two other written works by Goro, the
Libro segreto and the better known Istoria di Firenze (History of Florence), 1423—an
account of political events in the city, specifically, the relations of Florence with other citystates between 1380 and 1406. Here too he asserts that “the greatest advantage in
politics…lies with those who are so intimately familiar with all parts of the world….”
It is Dati’s rational attitude regarding his own city that may have led to his knowledge
of Mediterranean cities, and, ultimately, to place Florence at the center of this vast domain.
Hans Baron’s perception of Dati’s Istoria is tied to the author’s ideal of political action, his
need to understand the interrelation of events, his emphasis on reason in diplomacy, his
awareness of the invincible city-states, all born of his own practical experience (Baron,
1966).
Both the historical perspective of the Istoria and the cosmological and geographical
context of La sfera may serve as preludes to Bruni’s Laudatio, the supreme Renaissance
encomium to Florence. Above all, in Florence’s crises, Dati finds the equivalent of the
ancient concept of “civitas,” one generated by the city’s public institutions and its booming
economy (Baron, 1966; Gilbert, 1969). Whereas concern with public institutions is dominant
in the Istoria, the poem La sfera is bound to ancient cosmological principles. Alongside the
physical determinants of medieval and early Renaissance cities, included here are also
inferences of Plato’s Laws, or Vitruvius’ De Architectura (I, v, 1,2). Perhaps a fundamental
distinction governing the concept of the city in Dati’s time is that transformation between St.
Augustine’s image of the Civitate Dei, the City of God, to the Civitas humana, the product of
a society created by man (Bek, 1994). Perpetuating the concentric scheme of the ideal
medieval city in late trecento works by Villani and Salutati, Bruni incorporates these views of
Florence in his Laudatio. In this light, Dati’s more or less contemporary work may be
situated on the hinge joining the Middle Ages to the Renaissance.
Dati may well have recognized that the hegemony of Florence relied on the
interdependence of all city-states. But Dati’s affirmation of the effects of astrology on
human nature was written prior to the polemics against astrology by Pico, Pompanazzi, and
Savornarola. Dati accepts the system of celestial influence on the course of human events,
while at the same time admitting the possibility of, even the need for, its verification. By
plotting the course of celestial and terrestrial forces, charting the voyages of harbor and
inland cities within the Mediterranean sphere, providing data from centers of commerce and
places of pilgrimage, La sfera is still within a medieval frame. Although the dawn heralding
a new age of exploration is at hand, La sfera constitutes a medieval, rather than a Renaissance
interplanetary voyage.
Acknowledgements
I should like to express my gratitude to the organizers of the conference for the
opportunity to present this paper, and thereby open up new worlds to me. Early research was
generated by a fellowship at the Center for Advanced Study in the Visual Arts, National
Gallery of Art, Washington, D.C. Looking ahead, Giovanni Bignami has expressed interest
in translating La sfera from Italian to English. I have written an English version, but I am
certain that his expertise and elegance will justify a published translation of the text.
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