Henry of Hesse

(b. Hainbuch, Germany, 1325; d. Vienna, Austria, 11 February 1397)

physics , astronomy.

Actually nothing is known of the early life or career of Henry of Hesse (variously known as Henricus Hainbuch, de Hassia, de Langenstein, Hessianus) until 1363, the date he became a licentiate for the M.A. degree at the University of Paris. In 1364, 1370, 1371, 1372, and 1373 he took part in the examinations to which the future masters of arts had to submit. He was licentiate in theology in 1375 and doctor before 4 March 1376.

Following the Great Schism of 20 September 1378, Henry remained faithful to Pope Urban VI, while the Avignon pope Clement VII was supported by the French king Charles V. In June 1379 Henry wrote his first political treatise, Epistola pacis; and at the end of May 1381 he wrote a second tract, Epistola concilii pacis. In 1381 or 1382 Henry found it expedient to leave Paris for his homeland. For a while he stayed at the Cistercian monastery of Eberbach and then went to Vienna, where he spent the rest of his life and contributed greatly of the reorganization of the University of Vienna. He died on 11 February 1397 and was buried in the church of St. Stephen.

Henry’s earliest dated astronomical writing was the Quaestio de cometa, on the comet of 1368 and directed against the astrological treatise by John of Legnano (Bologna) on the same subject. In it he said that prognostications based on comets are worthless. Before 1373 Henry wrote two other treatises, Tractatus physicus de reductione effectuum specialium in vvirutes communes and De habitudine causarum et influxu naturae communis respectu inferiorum. In the former he mentioned impetus mechanics. Like Marsilius of Inghen in his Abbreviationes libri physicorum and undeniably dependent on him, Henry distinguished an impetus of circular motion from an impetus of rectilinear motion. Both treatises contain some peculiar biological ideas, such as speculations about the origin of new species and the mutation of existing ones. The mathematical expression of qualitative intensity in Oresme’s “art of latitudes” (there is a close relationship between the works of Oresme and Henry on natural philosophy, occult science, and astrology) led Henry to consider the possibility of the generation of a plant or animal from the corpse of another species, for example, of a fox from a dead dog.

The many astrological predictions evoked by the conjunction of Saturn and Mars in March 1373 caused Henry to reiterate his attack against the astrologers in his treatise Trctatus contra astrologos coniunctionistas de eventibus futurorum. Henry, likely with Oresme in mind, asserted that the foundations of astrology cannot be based on identically recurring astronomical experiences, since astronomical events are not of this type.

Henry also wrote a treatise on optics or perspective, the Questtones super communem perspectivam, which was largely derived from the Perspectiva communis of John Peckham, who is not mentioned. In it Henry referred to Euclid’s Elements, Aristotle’s Meteorology and On the Heavens and the World, and the genuine treatise of Archimedes, On Floating Bodies, the last of which he mentions under the title De insidentibus in humidum. It is unlikely that while mentioning this work he had in mind the Moerbeke translation De insidentibus aque. The Questiones super communem perspectivam consists of fifteen questions, the last of which deals with the rainbow. The maximum altitude of the iris is given as forty-two degrees, and it is stated that other colors are formed of varying proportions of white and black, light being white and opaqueness black.

BIBLIOGRAPHY

I. Original Works. The text of the Questiones super communem perspectivam will be in the forthcoming ed. by D. C, Lindberg and H. L. L. Busard. The work is preserved in MS Erfurt, Amplon. F. 380, 29r–40v: Biblioteca Nazionale, MS Codex S. Marci Floret. 202, convent, soppr. J.X. 19, 56r–85v; and Paris, MS Arsenal 522, 66r-88r. It is printed in a composite Mathematicarum opus (Valencia, 1504), 47r-65v, together with Bradwardine’s arithmetic and geometry; in the latter, questions 10 (“Utrum omnis visio fiat sub angulo”) and 11 (“Utrum omnes intensiones visbiles per species colorum apprehendantur sive indicentur”) are missing. Herbert Prucker, Studien zu den astrologischen Schriften des Heinrich von Langenstein (Leipzig, 1933), in addition to discussing Henry’s astrology, gives texts of the Quaestio de cometa, Tractatus contra astrologos, and other works.

II. Secondary Literature. A very good survey of the works of Henry of Hesse is in George Sarton, Introduction to the History of Science, III, pt. 2 (Baltimore, 1948), 1502–1510. Henry’s De reprobatione eccentricorum et epiciclorum is discussed, with long extracts, in Claudia Kren, “Homocentric Astronomy in the Latin West,” in Ists, 59 (1968). 269–281. Also of value are M. Clagett, Nicole Oresme and the Medieval Geometry of Qualities and Motions (Madison, Wis., 1968), pp. 114–121, which treats Henry’s use of the configuration doctrine; P. Duhem, le systéme du monde, VII (Paris, 1956). 569–575, 585–599; VIII (Paris, 1958), 483–489; X-(Paris, 1959), 138–141; and L. Thorndike, A History of Magic and Experimental Science, III (New York, 1934), 472–510.

H. L. L. Busard