Everything we do, our every objective, must be undertaken for the sake of... purity of heart... we must practice the reading of the Scripture, together with all the other virtuous activities... to hold our hearts free of the harm of every dangerous passion and in order to rise step by step to the high point of love.
John CassianAll of our holy fathers knew this and all with one accord teach that perfection in holiness can be achieved only through humility.
John Cassian...just as the edifice of all the virtues strives upward toward perfect prayer so will all these virtues be neither sturdy nor enduring unless they are drawn firmly together by the crown of prayer. This endless, unstirring calm of prayer... can neither be achieved nor consummated without these virtues. And likewise virtues are the prerequisite foundation of prayer and cannot be effected without it.
John CassianTrue spiritual knowledge has sometimes flourished most grandly in some who were without eloquence and almost illiterate. And this is very clearly shown by the case of the Apostles and many holy men, who did not spread themselves out with an empty show of leaves, but were bowed down by the weight of the true fruits of spiritual knowledge: of whom it is written in Acts: 'But when they saw the boldness of Peter and John, and perceived that they were ignorant and unlearned men, they were astonished' (Acts 4:13).
John CassianWherefore 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.
John Cassian