GERHARD GROOT, (1340-1384), in Latin Gerardus Magnus, founder of the society of "Brethren of the Common Life," was born in October, 1340, at Deventer, where his father held a good civic position. Other forms of the family name are Groote, Groet, and Groete. At the close of his school education, received partly at Deventer and partly at Aix-la-Chapelle and Cologne, Gerhard ("Gerrit" or " Geert") in his fifteenth year entered the university of Paris, where lie became firmly attached to the nominalism then in vogue, and where he made distinguished progress in almost all the branches of learning then cultivated, — canon law, medicine, astrology, and even magic being added to the theology and philosophy of the schoolmen. Shortly after his graduation in 1358, he returned to his father's house at Deventer, where, however, his stay was comparatively brief. We next hear of him as learning and teaching in Cologne; according to one account he studied also at Prague; and in 1366 he visited, on public business it is presumed, the papal court at Avignon. About this time he was appointed to a couple of canonries at Utrecht and Aix-la-Chapelle respectively, and the life of the brilliant young scholar was rapidly becoming luxurious, secular, and selfish, when a great spiritual change passed over him which resulted in a final renunciation of every worldly enjoyment. This conversion, which took place in 1374, appears to have been due partly to the effects of a dangerous illness, and partly to the influence of the learned and pious prior of the Carthusian monastery at Munnikhuizen near Arnheim, who had seriously remonstrated with him on the vanity of his life. During the next five years he devoted a considerable portion of his time to repeated and prolonged visits to the monastery of the Augustinian canons regular at Viridis Vallis (Groenendael near Brussels), whose prior, Johann Buysbroeck, a man of deep though somewhat mystical piety and of considerable literary power, could not fail to impress those who came in contact with him, and many of whose special views are unmistakably reproduced in the writings of Groot and his "fratres devoti." Between 1374 and 1379 Gerhard had also spent some three years in all at Munnikhuizen in study and prayer; and in the course of the last-mentioned year he left the privacy of the cloister, and having received ordination as a deacon, became a missionary preacher within the diocese of Utrecht. The success which followed his labours, not only in the town of Utrecht itself, but also in Zwolle, Kampen, Leyden, Delft, Gouda, Amsterdam, and many other places, was immense; according to Thomas a Kempis, the people left their business and their meals to hear his sermons, so that the churches could not hold the crowds that flocked wherever he came. The impartiality of the censures, however, which he directed, not only against the prevailing sins of the laity, but also against the heresy, simony, avarice, and impurity of the secular and regular clergy, soon provoked the uncompromising hostility of the entire body of the latter; and accusations of heterodoxy speedily began to be brought against him. It was in vain that Groot emitted a Publica Protestado, in which he declared that Jesus Christ was the great subject of his discourses, that in all of them he believed himself to be in harmony with the Catholic doctrine, and that he willingly subjected them to the candid judgment of the Roman Church. By a skilfully framed episcopal edict of 1383, which excluded from the pulpit all who had not received priest's orders, his public preaching was brought abruptly to an end; an appeal to Urban VI. was made in vain. Compelled thus to search for some other field of usefulness, Groot, in conjunction with his friend Florentius, a canon of Utrecht, began to superintend the labours of certain young men who employed themselves in transcribing manuscripts of church fathers and other authors ; from time to time as they met to receive payment for their work, he sought to edify them with religious exhortation. Ultimately the idea suggested itself that the little band might throw their earnings into a common fund and live together according to a fixed rule. The house of Florentius forth-with became a cloister of "fratres vitae communis," who were speedily joined by many new members, both clerical and lay, practised in a considerable variety of handicrafts; the general rule of the Augustinian order was adopted; it was also agreed that their daily bread should be shared in common, and that it should be earned, not begged. Groot's private estate sufficed for the establishment on like principles of a sisterhood who supported themselves by spinning, weaving, and needlework. After a comparatively brief life of singular energy, patience, and self-denial, Groot fell a victim to the plague at Deventer on the 20th of August 1384. Within fifty years of his death the " Brethren of the Common Life," also called "Fratres borne voluntatis" or "Fratres Collationarii," numbered seventeen collegiate churches in the Netherlands, and contributed somewhat extensively to theological literature. Thomas a Kempis, who wrote a Vita Gerliardi Magni, was trained under Gerhard himself at Deventer. The order disappeared at the time of the Reformation.

For a very clear and full account of the life of Groot, with an analytic and exhaustive catalogue of his extant works, reference may be made to the article on the "Brethren of the Common Life," by Hirsche, in Herzog's Real Enzyklopadie, ii. 679-696 (1878). The principal original authority is the work of Thomas a Kempis already referred to. See also Ullmann's Reformers before the Reformation, whose somewhat ex parte exposition of Groot's theological views, however, must be taken with reservations.