The Conferences Of John Cassian by John Cassian
Chapter VI. A comparison showing how a monk ought to keep guard over his thoughts.
Wherefore a monk's whole attention should thus be fixed on one point, and the rise and circle of all his thoughts be vigorously restricted to it; viz., to the recollection of God, as when a man, who is anxious to raise on high a vault of a round arch, must constantly draw a line round from its exact centre, and in accordance with the sure standard it gives discover by the laws of building all the evenness and roundness required. But if anyone tries to finish it without ascertaining its centre -- though with the utmost confidence in his art and ability, it is impossible for him to keep the circumference even, without any error, or to find out simply by looking at it how much he has taken off by his mistake from the beauty of real roundness, unless he always has recourse to that test of truth and by its decision corrects the inner and outer edge of his work, and so finishes the large and lofty pile to the exact point. So also our mind, unless by working round the love of the Lord alone as an immovably fixed centre, through all the circumstances of our works and contrivances, it either fits or rejects the character of all our thoughts by the excellent compasses, if I may so say, of love, will never by excellent skill build up the structure of that spiritual edifice of which Paul is the architect, nor possess that beautiful house, which the blessed David desired in his heart to show to the Lord and said: |I have loved the beauty of Thine house and the place of the dwelling of Thy glory;| but will without foresight raise in his heart a house that is not beautiful, and that is unworthy of the Holy Ghost, one that will presently fall, and so will receive no glory from the reception of the blessed Inhabitant, but will be miserably destroyed by the fall of his building.