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Frederick II of Hohenstaufen

Frederick II of Hohenstaufen

(b. Iesi, Italy, 26 December 1194; d. Castelfiorentino, Italy, 13 December 1250)

natural sciences.

Frederick II was the son of Emperor Henry VI and Constance of Sicily and was thus the grandson of both Frederick Barbarossa and Roger II of Sicily. He was crowned king of Sicily at Palermo in May 1198, following his father’s death in 1197. Upon his mother’s death six months later, Pope Innocent III became Frederick’s guardian and regent of Sicily, a situation not ended until 1208, when Frederick came of age. In 1210 Emperor Otto IV invaded Sicily; the young Frederick in turn challenged Otto’s rule in Germany the next year. The victory of his ally Philip II of France at Bouvines (1214) strengthened his position, and at Otto’s death in 1218 Frederick was left unchallenged in Germany and northern Italy; he was crowned Holy Roman emperor in 1220. Thereupon Frederick turned to the restoration of order in Sicily, a process finally completed with the promulgation of the Constitutions of Melfi (Liber Augustalis) in 1231. If taxation in the resulting nonfeudal, centralized state was high, the coinage was stable and justice relatively easy to obtain; with the creation of the University of Naples in 1224 the emperor sought to bring even professional education under his control.

A struggle between Frederick and the papacy was now inevitable: Rome was caught between the empire to the north and Sicily to the south and was threatened by their possible union. The conflict broke out first in 1227, when Gregory IX excommunicated Frederick as the latter was setting out on crusade; the pope was forced to release him in 1230, after he had returned from the East with possession of Jerusalem secured by negotiation. Frederick now momentarily favored the restoration of the German princes’ privileges, hoping to use the princes against the increasingly powerful Lombard cities. By 1239 Gregory IX had allied with the Lombard League and excommunicated the emperor once again. This time the conflict did not die away; war became general between imperial and papal factions, Ghibelline and Guelf, in Germany and Italy. The imperial position was severely weakened by the emperor’s defeat before Parma in 1248, but Frederick had begun to regain the advantage when he died of a sudden fever in 1250.

What immediately strikes anyone attempting to understand Frederick II is his intense curiosity about the particulars of nature, most unusual in an age that was forever seeking universals. His contemporaries were struck by this too, as the famous stories recounted by the monk Salimbene show—the story, for example, that Frederick once disemboweled two men after giving them a hearty meal in order to determine the relative effects of sleep and exercise (he had sent one hunting) upon digestion. True or not—Salimbene was a Guelf partisan—the tale shows how people expected the emperor to behave. Anecdotes like this were of a piece with others about the exotic menagerie (which at one time or another actually included monkeys, camels, a giraffe, and an elephant) that moved with him in Italy and Germany.

That a serious spirit of inquiry was behind all this show is easily seen in the “many-sided patronage of learning” so prominent at Frederick’s court. His kingdom of Sicily, heir to both the Greek and the Islamic cultures, had been a center of science and translation in the twelfth century under his grandfather, Roger II. Frederick continued this tradition, drawing scholars of widely different backgrounds and interests to his court. Two seem to have been of particular importance as advisers: the famous Michael Scot (from ca. 1228 until death, Ca. 1236) and a Master Theodore (ca. 1235–1250). The mathematician Leonardo Fibonacci, although not attached to the court, was well known there; the revised version of his Liber abaci is dedicated to Michael Scot, and the Liber quadratorum to Frederick himself. In addition, Frederick was in communication with other scholars—Christian, Jewish, and Muslim—far from court.

The court philosophers were regularly called upon to satisfy Frederick’s curiosity. Michael Scot has left us a questionnaire put to him by the emperor, containing a wide range of problems: Precisely where are heaven, hell, purgatory, and the several abysses in relation to the earth and to each other? Why are there both sweet and salt waters on the earth, and whence do they arise? What gives rise to volcanic fire and smoke? We know of still other questions—metaphysical, mathematical, and optical (why do objects partly immersed in water appear bent?)—sent to Muslim and Jewish philosophers in Spain and Egypt. No program lay behind these questions; it was simply that the accepted commonplaces of experience regularly stirred Frederick to inquiry.

Such questions may show the breadth of Frederick’s interests but not the depth of his own knowledge; the latter is fully revealed only in the famous De arte venandi cum avibus, a composition developed by Frederick over some thirty years, that we possess in a draft completed ca. 1244–1248, in part later emended by his son Manfred. (A finished version has apparently been lost, probably at Parma.) The first of the extant six books, which was conceived by Frederick as a necessary preliminary to the technical substance of falconry, is a remarkable survey of general ornithology: it moves from the classification of birds to their feeding habits, migration, mating, nesting, anatomy and physiology, flight, and molting. As impressive as the collected material is the systematic personal observation on which it is obviously based; Frederick describes his experimental determination that vultures locate their food by sight rather than by smell (ch. 10) and tells of his successful efforts to duplicate in Apulia the artificial incubation of eggs by sunlight that he had observed in Egypt (ch. 23). The later books are more technical and specialized, treating the training and rearing of falcons (book II), the use of the lure (book III), and the techniques of hawking with various birds (books IV-VI). But still they rest upon the emperor’s own experience. His passion for the sport is apparent even in what survives of his correspondence, which shows him turning all his administrative resources to the instruction and supervision of his falconers. He was in fact away hawking at the moment when his siege of Parma was so disastrously broken.

Frederick’s attitude in De arse venandi toward Aristotle as zoologist is of some interest and might be likened to that of a field naturalist toward a research biologist: critical if sometimes grudgingly respectful of the other’s specialized knowledge. He points out that experience shows that Aristotle’s deductions cannot always be relied upon and notes regretfully that “he was ignorant of the practice of falconry,” but he refers his readers for supplementary taxonomic and embryological detail to Aristotle’s Historia animalium (which had been translated from Arabic by Michael Scot at least a decade before his arrival at Frederick’s court, and included the De animalibus, De partibus animalium, and De generatione animalium). At one point (book I, ch. 27) he even draws upon the (pseudo-) Aristotelian Mechanica to argue that the primary wing feathers must have the greatest power to carry a bird forward in flight. It remains characteristic of the emperor that he would disdain no source of knowledge, as long as it could be controlled by his own experience and judgment.


I. Original Works. The De arte venandi cum avibus exists in MS in two traditions, one including only the first two books, ther other including all six. The two earliest MSS of the former tradition (MS Vat. Pal. Lat. 1071, copied perhaps as early as 1260, and MS Paris BN Fr. 12400, probably copied from the Vatican MS ca. 1310) are illustrated with a series of remarkable miniatures that presumably reflect Frederick’s archetype; Haskins considered that the emperor himself had given the directions for these illustrations, which in the Vatican MS are strikingly faithful to nature. This two-book tradition has been twice edited, by Johann Velser (Augsburg, 1596) and by Johann Gottlieb Schneider (Leipzig, 1788–1789); the six-book version has been published (although without editorial remarks of any sort) by Karl Arnold Willemsen, 2 vols. (Leipzig, 1942). Willemsen has also reproduced many of the illustrations accompanying the De arte venandi in the Paris MS under the title Die Falkenjagd. Bilder aus dem Falkenbuch Kaiser Friedrichs II (Leipzig, 1943). An English trans. of all six books of Frederick’s work has been published by Casey A. Wood and F. Marjorie Fyfe (Stanford, 1943); on pp. lvii-Ixxxvii the editors examine the known MSS of the De arte venandi and cite two German trans. (of 1756 and 1896) of the two-book tradition besides the Velser and Schneider eds. C. H. Haskins’ article “The De arte . . .,” referred to below, also discusses the MS tradition of the work and forms the basis of the Wood-Fyfe treatment.

II. Secondary Literature. A full if somewhat overly romantic study of Frederick’s life and thought is Ernst Kantorowicz, Kaiser Friedrich der Zweite, 2 vols. (Berlin, 1927; repr. Düsseldorf-Munich, 1963); an English trans. by E. O. Lorimer, Frederick the Second, 1194–1250 (London, 1931; repr. New York, 1957), omits the original’s bibliography and footnotes. Kantorowicz treats Frederick’s attitude toward science and the natural world with considerable insight on pp. 308–327 of the German version (pp. 334–365 of the English version). His treatment owes a great debt to the still fundamental articles of Charles Homer Haskins: “Science at the Court of the Emperor Frederick II,” “Michael Scot,” and “The De arte venandi cum avibus of Frederick II,” collected in his Studies in the History of Mediaeval Science (Cambridge, Mass., 1924; repr. New York, 1960), pp. 242–326. A number of more recent special studies have been brought together in Gunther Wolf, ed., Stupor mundi. Zur Geschichte Friedrichs II. von Hohenstaufen, vol. CI of Wege der Forschung (Darmstadt, 1966), which includes a considerable extract from Martin Grabmann’s Mittelalterliches Geistesleben, “Kaiser Friedrich II. und sein Verhältnis zur aristotelischen und arabischen Philosophie” (pp.134–177 of Stupor mundi). The question of Frederick’s knowledge and use of contemporary medical and natural-philosophical doctrine has been further studied in two articles by Johannes Zahlten: “Medizinische Vorstellungen im Falkenbuch Kaiser Friedrichs II.,” in Sudhoffs Archiv für Geschichte der Medezin und der Naturwissenschaften, 54 (1970), 49–103; and “Zur Abhängigkeit der naturwissenschaftlichen Vorstellungen Kaiser Friedrichs II. von der Medizinschule zu Salerno,” ibid., 173–210.

Michael McVaugh

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