...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 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