A pious and learned monk of the Cistercian manastery of Heisterbach near Bonn, born about 1170 at or near Cologne where he had Ensfried, Daen of St. Andrew, as teacher. He also heard at the Cathedral School the lectures of the learned Rudolph, who had previously been a professor at the University of Paris. Under these two competent teachers Caesarius studied the theology of St. Ambrose, St. Augustine, St. Jerome, and St. Gregory the Great; the philosophy of Boethius, and the literary masterpieces of Virgil, Ovid, Senca, and Claudian. He was a gifted and diligent scholar and upon the completion of his studies was thoroughly conversant with the writings of the Fathers of the Church and master of a refined and fluent Latin style. Like most German educators of his time, he was a theologian rather than a philosopher and looked with suspicion upon the rationalistic tendencies of scholastic philosophy, as it was taught in many schools of France. Acting on the advice of Gevard, Abbot of Heisterbach, Caesarius entered that monastery in 1199 and after some time was appointed to the responsible office of master of novices. It was his duty to imbue the candidates with the spirit of austere asceticism which then animated the Cistercian Order, and to instruct them in the necessary knowledge of theology. His fame as teacher soon spread far beyond the walls of his monastery and, yielding to requests from various quarters, Abbot Henry, Gevard's successor, asked Caesarius to write an abstract of his teachings. This occasioned the famous "Dialog". In 1228 Caesarius was made prior of his monastery and thenceforth accompanied the abbot on many official visits in Germany and Friesland.

Caesarius was one of the most popular writers of the thirteenth century. The numerous manuscripts, still extant, of many of his works show how greedily they were read by his contemporaries. About the year 1238 he wrote the so-called "Epistola Catalogica", a list of thirty-six works which he had published up to that date. By far the best known and most important work, however, of Caesarius is his "Dialoge of Visions and Miracles" in twelve books (Dialogus magnus visionum atque miraculorum, Libri XII). It struck the fancy of his thirteenth-century readers to such an extent that it became probably the most popular book in Germany at that time. The people that day of the later Crusades, owing greatly to the many fabulous stories brought from the Orient by returning crusaders, had an irresistible liking for the strange and marvelous. Like a true child of his times, Caesarius related in all seriousness the most incredible stories of saints and demons, but scrupulously avoids whatever may endanger the principles of true piety and sane morality. His purpose was not to relate facts of history, but to entertain and edify his readers. He accomplished this purpose most successfully. Though his "Dialogue" is merely a collection of ascetical romances, it has become one of the most important sources for the history of civilization during the thirteenth century. It presents to our view a living panorama of all that the student of the history of civilization cares to know. Popes and emperors, priests and monks, rich and poor, learned and illiterate, good and bad, all sorts and conditions of men, pass before our vision as if we were living among them. More than fifty manuscripts of the "Dialogue" are extant, and seven printed editions are known. The latest, in two volumes, was prepared by Strange (Cologne, 1851); an index to the same (Coblenz, 1857). Another work of Caesarius identical in historical value with the preceding is his "Eight Books of Miracles" (Volumen diversarum visionum seu miraculorum, Libri VIII). Of this work only a fragment of three books is known; it was carefully edited with valuable critical notes by Meister (Rome, 1901). Though not in the form of a dialogue, it has the same scope as the preceding work. Because, despite diligent researches, no other fragments of the work could be found, Meister suspects that Caesarius never completed it.

The principal historical work of Caesarius is the life of the murdered St. Engelbert, Archbishop of Cologne (1216-25), entitled "Actus, pasio et miracula domini Engelberte". It is composed of three books, the first of which is devoted to an impartial estimate of the character of the great archbishop; the second narrates with graphic vividness and tender pathos the circumstances of the sad catastrophe, while the third book, which was added ten years later (1237), recounts the miracles wrought through the relics of the archbishop after his death. Since the biography was begun immediately after the death of Engelbert, the auther did not fully comprehend what fatal effects the murder of the best and most trusted advisor of the young King Henry was to have upon the future history of Germany; but in depicting the character of his hero, and in narrating the particulars of the foul deed, Caesarius shows himself a master. There is scarcely another biography of the Middle Ages so artistically executed and so thoroughly reliable. It was printed by Surius in the "Acta Sanctorum", 7 November (1st ed. 1574; 2d ed., Cologne, 1617); by Gelenius (Cologne, 1633); finally, with the omission of the third book, by Bohmer in his "Fontes Rerum Germanicarum" (Stuttgart, 1843-68), II, 294-329. A good German translation was brought out by Bethany (Elberfeld, 1898). Caesarius also wrote a biography (the oldest extant) of St. Elizabeth of Hungary, which, however, has never been printed, with the exception of a few fragments published by Montalembert, in "Sainte Elisabeth" (Paris, 1903), and by Borner, in "Neues Archiv der Gesellschaft fur altere deutsche Geschichtskunde" (Hanover, 1888), 503-506. It is merely a recasting of the "Libellus de dictis quatuor ancillarum", a list of the Archbishops of Cologne between the years 94-1238, with important biographical data and cincise but valuable reflections on the history of the times. Up to the accession of Philip of Heimsberg (1167) it is based on an older chronicle, but the rest is an original work of Caesarius. It was published by Bohmer, op. cit., II, 271-282, and by Cardauns in "Mon. Germ. Hist: Script.", XXIV, 332-47. When still quite young, Caesarius began to write sermons, most of which have been collected by Coppenstein: "Homiliae sive fasciculus moralitatum" (Cologne, 1615). These sermons, though inferior in thought and style to the oratorical masterpieces of his great Franciscan contemporary, Berthold of Regensburg, were highly esteemed on account of their practical character and their suitability to the conditions of his hearers.

KAUFMANN, Caesarius von Heisterbach (2d ed., Cologne, 1862); SCHONBACH in Sitzungsberichte der k. Akademie der Wissenschaften, No. 144 (Vienna, 1902); MEISTER, Die Fragmente der Libri VIII miraculorum des Caesarius von Heisterbach in 13. Supplement-Heft zur Römischen Quartalschrift (Rome, 1901); PONCELET, Note sur les Libri VIII miraculorum in Analecta Bollandiana (Brussels, 1902); HAUCK, Kirchengesch. Deutschlands (Leipzig, 1903), IV, 454 sqq.; WATTENBACH, Deutschlands Geschichtsquellen (Stuttgart, 1904); CARDAUNS in Allg. d. Biogr., s. v. (Leipzig, 1875); UNKEL in Annalen des hist. Vereins fur den Niederrhein, No. 34 (Cologne, 1879), 1-67; HOFER, ibid., No. 65 (Cologne, 1898), 237 sqq.; KESSEL in Kirchenlex., s.v.

MICHAEL OTT