The saint honored by the Church today held together in himself two aspects of the Church's life that at first glance appear disparate.  As a monk, St. Augustine observed diligently the rigors of the regular life.  He belonged to, and eventually became superior of, St. Andrew's Monastery in Rome, which had been established by St. Gregory the Great on his family's estate.  Soon after the monastery's foundation, Gregory was called from its prayerful silence when elected Bishop of Rome.  Despite the absence of its founder, the monastery continued to flourish, thanks in no small part to the wise leadership of Augustine.  A few years after Gregory's election as pope, pressed to restore the Island of Britain to the practice of the faith, the saintly pontiff went to his friend, Augustine, and asked him to spearhead a missionary expedition to the Angles.  In so doing, Gregory drew on a truth he discovered in his own life, that the monastery can be an excellent training ground for pastoral activity.

Called therefore from the cloister, Augustine and his companions entered the Church's mission fields in Britain, where maintaining their monastic disciplines while preaching they converted the Kingdom of Kent and restored southern England to the grace of Catholic faith.  For centuries afterwards, English Catholicism maintained the monastic traditions of its first apostles and thereby witnessed the complementarity of the cloister and the cathedra to the wider Church.

First tried by Gregory the Great, the papacy would employ this missionary strategy again in the twelfth and thirteenth centuries by sending Cistercian monks to preach against the Albigensians in France.  As before, this pastoral plan would prove providential.  In the course of their preaching, these evangelical Cistercians were joined by a traveling Spanish canon, Dominic de Guzman, who, drawing from their witness and experience, founded the Order of Preachers in part to provide the Church a more fruitful and permanent experience of the union of contemplation and action in preaching.

For more on the life of St. Augustine of Canterbury and the fruits of his labors in England, click here and here.