Perfection... is clearly not achieved simply by being naked, by the lack of wealth or by the rejection of honors, unless there is also that love whose ingredients the apostle described (cf. I Cor. 13) and which is to be found solely in purity of heart. Not to be jealous, not to be puffed up, not to act heedlessly, not to seek what does not belong to one, not to rejoice over some injustice, not to plan evil - what is this and its like if not the continuous offering to God of the heart that is perfect and truly pure, a heart kept free of all disturbance?
John CassianMore John Cassian quotes
The apostles were very sure that everything of theirs which had to do with salvation was a gift to them from God. 'Increase our faith'. They did not presume that the fullness of faith would come to them merely because they freely opted for it. They believed, rather, that it was a gift of God which would have to be granted to them.
John Cassian
... a Christian is quite certain to fall into the same sins which he condemns in another with merciless and inhuman severity, for 'a stern king will fall into misfortunes,' and 'one who stops his ears so as not to hear the weak, shall himself cry, and there shall be none to hear him' (Prov. 13:17; 21:13).
John Cassian