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Giles (Aegidius) of Rome

Giles (Aegidius) of Rome

(b. Rome, Italy, before 1247; d. Avignon, France, 22 December 1316)

physics, astronomy, medicine.

Often called, probably mistakenly, Giles Colonna, he joined the Hermits of St. Augustine while very young. He pursued his studies in paris where he was a disciple of Thomas Aquinas and became baccalarius sentenliarius in 1276. In march 1277 Étienne Tempier, the bishop of Paris, delivered his famous condemnation of Aristotelianism and Averroism. His teaching and writings having thus been censured, Giles was obliged to leave the city. He did not return for several years. In 1285 he received the licentia decendi in Paris at the request of Pope Honorius IV, after having retracted several of his theses. From 1285 to 1291 he taught theology.

The Hermits of St. Augustine revealed exceptional confidence in deciding as early as 1287 that his opinions should be admitted and upheld throughout the order, and they chose him for their general on 6 January 1292. On 25 April 1295 Giles was named archbishop of Bourges by Pope Boniface VIII. He died during a stay at the papal court at Avignon.

Although mainly a philosopher and theologian, Giles frequently dealt with problems relating to natural philosophy, notably in his commentaries on Aristotle. Moreover, he did so in a style distinctive enough to place him in the first rank of those thinkers who have made a positive contribution to the scientific thought of their time (see Maier, Die Vorläufer Galilies, p. 2). One of the first theses that Giles defended was the unity of substantial form, which he presented—without, however, daring to apply it to man in his early commentary on the De anima, written before 1275. He returned to it in his Theoremata de corpore Christi and then, in 1278, in his commentary on the Physics, written around 1277, that he considered scientific problems.

Among Giless’s theses that have attracted the attention of more recent historians of science are those relating to quantity, which led him to admit the existence of natural minima below which concrete material substance cannot exist and which thus imply an atomistic theory of matter. The study of movement induced him to investigate the nature of a vacuum, to which he attributed a kind of suction force, observable with the aid of the clepsydra, the cupping glass, or the siphon. He arrived at a curious theory according to which only the resistance of the material medium, and not the distance traversed, enables movement to occur in time; movement in a vacuum would be non in tempore. His observations on the accelerated motion of falling bodies have similarly been noted: he observed that the speed of a freely falling body depends not on the proximity to its destination but on the traversed distance from its point of departure.

Several of these theories reappear in his later works, mainly in the Quodlibeta (1286–1291) and the Expositioand Quaestiones on the De generatione et corruptione. The latter two became classics, and were often utilized by such fourteenth-century physicits as Buridan and Marsilius of Inghen, who considered Giles the communis expositor of the De generatione.

Giles was also interested in other questions, which he often dealt with in short treatises that are difficult to date. Especially noteworthy are De materia coeli, which takes the position—against Aristotle, Thomas Aquinas, and the majority of contemporary scholars— that celestial matter is identical to that of the sublunary world; De intentionibus in medio, on the nature of light and its propagation; and De formatione corporis humani in utero, an embryological treatise inspired by Ibn Rushd. Giles developed his cosmological views to their fullest at the end of his career, in his commentary on the second book of the Sententiae of Peter Lombard and in his In hexaemeron, both finished during his episcopacy. Undoubtedly influenced by the censure of 1277, he admitted the possibility of a plurality of worlds. Furthermore, he renounced Aristotle’s theory of homocentric spheres in favor of that of eccentrics and epicycles, inherited from Ptolemy and Simplicius.


I. Original Works. It is impossible to give a complete list here of the very numerous works that Giles has left us. For that, one should consult the bibliographies by Lajard, Boffito, Glorieux, and Bruni (see below). Early eds, of the majority of Giles’s writings have recently been reproduced (18 vols., Frankfurt am Main, 1964–1968). A list of modern eds. whose introductions are of the most interest or which concern Giles’s scientific thought follows.

De erroribus philosophorum: P. Mandonnet. ed., in Siger de Brabant, 2 vols. (Louvain, 1908), II, 3–25; and J. Koch, ed., with English trans. by J. O. Riedl (Milwaukee, 1944); koch text repro (Milan, 1965).

De ecclesiastica potestate: G. Boffito, ed., with intro. by G. M. Oxilia (Florence, 1909); R. Scholz, ed. (Weimar, 1929; repr., Aalen, 1961).

Theoremata de esse et essentia: E. Hocedez, ed. (Louvain. 1930); English trans. by M. V. Murray (Milwaukee, 1953).

De plurificatione intellectus possibilis: H. Bullotta Barracco, ed.(Rome, 1957).

Quaestio de natura universalis: G. Bruni, ed., in Collezione di testi fzlosofici inediti, II (Naples, 1935).

Other, previously unpublished “Quaestiones” were published by Bruni, in Analecta augustiniana, 17 (1939), no. 1, 22–66; no. 2, 125–157; no. 3, 197–207, 229–245; and by V. Cilento, in Medio evo monastico e scolastico (Milan, 1961), pp. 359–377.

II. Secondary Literature. For his biography and literary and doctrinal history, see G. Bruni, Le opere di Egidio Romano (Florence. 1936); “Saggio bibliografico sulle opere stampate di Egidio Romano,” in Analectaaugustiniana, 24 (961), 331–355; “Rari e inediti egidiani,” in Giornale critico della filosofia italiana, 40 (1961), 310–323;P; Glorieux, Repertoire des maitres en théologie de Paris au XIIIesiècle; 2 vols. (Paris. 1933–1934), II, 293–308; E. Hocedez, “Henri de Gand et Gilles de Rome,” in Richard de Middleton (Louvain, 1925), pp. 459–477; “Gilles de Rome et saint Thomas,” in Mélanges Mandonnet, 2 vols. (Paris, 1930), I, 385–410; “La condamnation de Gilles de Rome,” in Recherches de théologie ancienne et médiévale, 4 (1932), 34–58; F. Lajard, “Gilles de Rome, religieux augustin théologien,” in Historie littéraire de la France, XXX (Paris, 1888), 421–566; J. S. makaay, Der Traktat des Ägidius Romaus über die Einzigkeit der substantiellen Form (würzburg, 1924); P. Mandonnet, “La carriéere scolarie de Gilles deRome,” in Revue des sciences philosophiques et théologiques, 4 (1910), 481–499; N. Mattioli, Studio critico sopra Egidio Romano Colonna (Rome, 1896); and Z. K. Siemaitkowska, “Avant l’exil de Gilles de Rome, au sujet d’une dispute sur les theoremata de esse et essentia de Gilles de Rome,” in Mediaevalia philosophica Polonorum, 7 (1960), 3–48.

Further information on Giles’s MSS has been provided by F. Pelster, in Scholastik, 32 (1957), 247–255; and for Polish MSS by W. Sénko, in Mediaevalia philosophica Polonorum, 7 (1960), 22–24, and 11 (1963), 146–151; in Augustiniana, 12 (1962), 443–450; and by Z. K. Siemiatkowska, in Mediaevalia philosophica Polonorum, 11 (1963), 5–22.

Giles’s scientific thought is discussed in P. Duhem, Études sur Léonard de Vinci, II (Paris, 1909); Le systèMay du monde, IV, VI-X (Paris, 1954–1959); A Maier, Die Vorläfer Galieis im 14. Jahrhundert (Rome, 1949); Zwei Grundprobleme der scholastischen Naturphilosophie, 2nd ed. (Rome, 1951); An der Grenze von Scholastik und Naturwissenschaft, 2nd ed, (Rome, 1952); Metapgysiche Hintergründe der spätscholastischen Naturphilosophie (Rome, 1955); and G. Sarton, Introduction to the History of Science, II, pt. 2 (Baltimore, 1931), 922–926.

Jean ChÂtillon

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