GROOT, GERHARD otherwise Gerrit or Geert Groet, in Latin Gerardus Magnus, a preacher and founder of the society of Brothers of Common Life (q.v.), was born at Deventer in the diocese of Utrecht. After studying at Paris, where he imbibed nominalistic tendencies, and at Cologne, he visited the papal court at Avignon about 1366. Soon afterwards he was appointed to a canonry in Utrecht and to another in Aix-la Chapelle. In 1374 he experienced a conversion which led him to retire for three years to the Carthusian monastery at Munnik huizen near Arnhem. In 1379, having received ordination as a deacon, he became missionary preacher throughout the diocese of Utrecht. The success which followed his labours 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 them. His violent denunciation of the prevailing sins of the laity and clergy provoked hostility, and accusations of heter odoxy were brought against him.
It was in vain that Groot emitted a Publics Protestatio. The bishop was induced to issue an edict which prohibited from preach ing all who were not 'n priest's orders, and an appeal to Urban VI. was without effect. At some period (perhaps 1381, perhaps earlier) he visited the famous mystic Johann Ruysbroeck, prior of the Augustinian canons at Groenendael near Brussels; at this visit was formed Groot's attraction for the rule of the Augus tinian canons. At the close of his life he was asked by some clerics to form them into a religious order, and Groot resolved that they should be canons regular of St. Augustine, but he died before a foundation could be made. In 1387, however, a site was secured at Windesheim, and here was established the monastery that became the cradle of the Windesheim congregation of canons regular. Groot lived to preside over the first days of his other creation, the society of Brothers of Common Life. He died of the plague at Deventer in 1384.
(E. C. B.; X.)