With these words Vergil calls the attention of Dante and ourselves to the presence of that astrologer in the fourth division of the eighth circle of the Inferno among those spirits who in life had tried to pry too far into the future and were condemned henceforth to look backwards with turned heads. This is all that Dante says of Bonatti, although Benvenuto of Imola, the fourteenth century commentator upon the Divine Comedy, adds a number of tales concerning him, some of which may be true but most of which are stock stories like that of the speaking brazen head, told of many other medieval men of learning. But we may perhaps associate Bonatti and Dante in our minds a little further. Forlì, Bonatti’s native city, lies almost in a direct line between Florence, where Dante lived his early life, and Ravenna, where he ended his exile. Indeed, Filippo Villani[2631] and Fossi[2632] would persuade us that Guido Bonatti, too, was born a Florentine but, like Dante, became an exile from the town of his birth and called himself a native of Forlì because he came to hate the place of his birth which he had left on account of the strife of political factions. Finally, Bonatti and Dante had a common interest in astronomy.[2633]
The Liber astronomicus of Guido Bonatti.
The most important astrological work produced in Latin in the thirteenth century seems to have been the Liber astronomicus of this Guido Bonatti,[2634] which is a voluminous work divided into some ten or a dozen treatises.[2635] In the preface, after some of the usual devout opening phrases of medieval authors, Guido states that he writes the book particularly for the use of his nephew, that the work will be “long and prolix” and that on this account he will not include “disputations nor many proofs.” He proposes to compile a work from past authors which can be understood by those who do not yet know much of other sciences “and especially for your use, Bonatus, my nephew.” Indeed, the annalist of Forlì states that Bonatti expounded the doctrine of astrology so clearly in this book that “it seemed as if he wished to teach women astrology.”[2636] Guido employs such classical authorities as Ptolemy, Hermes, and Dorotheus, but still more such Arabian astrologers as Alcabitius, Albumasar, Messahala, and Thebit ben Corat.[2637] He also states that he has made additions of his own,[2638] and many passages demonstrate that he has made detailed practical application to the present problems of medieval life of the principles of his art established in the past. The popularity and influence of Guido’s work is attested by the numerous manuscripts, including an interesting de luxe manuscript of it and other astrological treatises made for the use of Henry VII of England, whose picture is given in the midst of Bonatti’s text.[2639] There are also several printed editions of the Latin text and translations of the work into several modern languages. There is an Italian translation of it in a manuscript in the Laurentian library at Florence; a German translation was printed at Basel in 1572; and an English translation by William Lilly appeared in print at London in 1676.[2640] Thus Dante’s consignment of Bonatti’s soul to hell does not seem to have kept people from reading his Liber astronomicus.
Career of Bonatti.
The battle of Valbona, fought in 1277, seems to be the latest event mentioned by Bonatti. He also speaks of having himself seen many evidences of the cruelty of Ezzelino, and of that tyrant’s death, which occurred in 1259. He was alive as early as 1223, when he mentions having seen a certain man.[2641] Guido seems to have been a professor at the university of Bologna. He must have died before 1300, when Dante’s visit to the Inferno is supposed to have occurred. Bonatti’s death, however, would seem to have been comparatively recent, since the Annals of Forlì[2642] represent him as playing a prominent part in the defense of that town in 1282 by the famous captain, Guido of Montefeltro, against a large force sent by Pope Martin IV. Though Bonatti himself was loyal, it was in a wheat field belonging to him that conspirators gathered in a vain attempt to betray the town, while the enemy later encamped outside the city in another field belonging to him and called, “Of the oak tree.”
Then Guido of Montefeltro, we are told, “captain of the people of Forlì, together with lord Guido Bonatti, a citizen, philosopher, and most eminent astrologer, having called the people together in the public square,” instructed them as to the strategem of a mock withdrawal from town and subsequent return by which he intended later to take the superior forces of the enemy unawares after they had entered the town in triumph and were overcome by feasting and drinking. The strategem turned out a complete success, and the Annals give much of the credit to Bonatti, by whose counsel, art, and forecasting the future it is said to have been planned. He was wounded in the battle, while carrying medicines, but this too he had foreseen and foretold. Later, when the pope sent more mercenary troops into Romagna, Forlì deemed it prudent to submit, and Guido of Montefeltro transferred his military activities elsewhere and finally, we are told, made his peace with the pope and spent his declining years in the Franciscan Order. Some say that Bonatti followed his patron into the convent, but it seems very improbable in view of the hard things which he had said of the friars. On the other hand, judging from the number of Franciscans who have written works on astrology and astrological medicine, he might not have found such retirement entirely uncongenial, and need scarcely have surrendered his astrological views in consequence.
Arrangement of the Liber astronomicus.
But we turn to the contents of the Liber astronomicus. Bonatti’s first treatise is a general introduction in which he defines his subject, discusses its utility, and meets the objections of its opponents. The second treatise[2643] deals with the signs of the zodiac and their characteristics and subdivisions. The third treatise, in two parts,[2644] deals with the planets, their influences on things on earth and their effects on one another. The fourth treatise deals chiefly with conjunctions. The remaining treatises comprise 146 considerations affecting astrological judgments, another brief introduction of three chapters to the subject of judgments,[2645] discussions of the four chief departments of astrological prediction, interrogations, elections, revolutions, and nativities, and a final treatise upon prognostication of changes in the weather.[2646]
Astronomy and astrology.
As the title, Liber astronomicus, shows, Bonatti generally uses the word “astronomy” where we should say “astrology” and vice versa. He states, for instance, that nativities, elections, interrogations, and revolutions are four varieties of “astronomy,” which he distinguishes from other forms of divination.[2647] He also says, however, that the words “astronomy” and “astrology” may be used interchangeably. He regards both as of great value in the study of first philosophy. Through these sciences we come to know impassive and unalterable creatures who cannot be changed into any other essence, and through these creatures we can attain to as much knowledge of the Creator as the human mind can reach. Nobler than the profession of the physician who deals with the four inferior and corruptible elements is that of the astrologer whose concern is with superior and incorruptible bodies composed of the fifth essence.[2648]