c.480 - 543
Saint Benedict of Nursia was the creator of Western monasticsm and the founder of the monastery at Monte Cassino, where he established the Benedictine order.
Benedict lived for three years in solitude in a cave near Rome. Later he established twelve monasteries with 12 monks each. The Benedictine rule he established required such things as a year probation, a vow to remain in the monastery until death, absolute poverty, manual labour, and spiritual reading.
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From the Catholic Encyclopedia:
St. Benedict and his Order