“Monks to whom for Christ’s sake the world is crucified and who are crucified to the world, must sedulously guard against covetousness, seeing that it is wrong for them not only to be possessed of superfluities, but even to desire them. It is not what they possess that matters, but rather how their wills are affected by their possessions. Those who have left all things to follow Christ the Lord with the cross of daily fear have treasure in heaven. Therefore, as they are to possess much in heaven, they ought to be content with little, nay, with the barest necessaries on earth, remembering that in monks covetousness is a leprosy.”
St. Columbanus (540-615) in The Rule of St. Columbanus 4.