Saint John Cassian. "On the Holy Fathers of Sketis And on Discrimination". Written for Abba Leontios. From Philokalia, Vol. 1.
'From all that has been said, we may conclude that nothing leads so surely to salvation as to confess our private thoughts to those fathers most graced with the power of discrimination, and in our pursuit of holiness to be guided by them rather than by our own thoughts and judgment. Nor should the fact that we may encounter an elder who is somewhat simple-minded or lacking in experience either prevent us from confessing to the fathers who are truly qualified, or make us despise our ancestral traditions. Many texts from the divine Scriptures make it clear that the fathers did not say these things according to their own-lights, but were inspired by God Himself and by the Scriptures to hand down to their successors the tradition of asking advice from those who had traveled far along the spiritual path. This is borne out especially by the story of the holy Samuel, who from infancy was dedicated by his mother to God and was granted communion with Him. He still did not trust his own thoughts, and in spite of having been called three times by God, he went to the elder, Eli, and was instructed and guided by him about how he should answer God (cf. 1 Sam. 3:9-10). Although God called him personally, none the less He wanted Samuel to receive the guidance and discipline of the elder, so that by means of this example we too might be led towards humility.
'When Christ Himself spoke to Paul and called him, He could have opened his eyes at once and made known to him the way of perfection; instead He sent him to Ananias and told him to learn from him the way of truth, saying: "Arise and go into the city, and there you will be told what you must do" (Acts 9:6). In this manner He teaches us to be guided by those who are advanced on the way, so that the vision rightly given to Paul should not be wrongly interpreted; otherwise it might lead later generations presumptuously to suppose that each individual must be initiated into the truth directly by God, as Paul was, and not by the fathers.
"That this is the correct interpretation of these incidents can be seen not only from what is said here, but also from St Paul's own actions. He writes that he went up to Jerusalem to see Peter and James, and "laid before them the gospel I preach ... in case I was running or had run in vain" (Gal. 2: 2); and he did this even though the grace of the Holy Spirit was already with him, as can be seen from the miracles which he performed. Who, then, can be so proud and boastful as to be satisfied with his own judgment or opinion, when St Paul himself admits that he needs the advice of those who were apostles before him? All this shows with complete clarity that the Lord reveals the way of perfection only to those guided to it by their spiritual fathers. This accords with what He Himself has said through the Prophet: "Ask your father, and he will show you; your elders, and they will tell you" (Deut. 32:7).
'We should therefore make every effort to acquire for ourselves that gift of discrimination which is able to keep us from excess in either direction. For, as the fathers have said, all extremes are equally harmful. It is as dangerous to fast too much as it is to overfill the stomach; to stay awake too long as to sleep too much; and so on. I myself have known monks who were not defeated by gluttony, but were undermined by immoderate fasting and lapsed into gluttony because of the weakness caused by this fasting. Indeed, I can remember having experienced this one myself. I had kept such strict control over my food that I forgot what it meant to be hungry, remaining without food for two or three days and still feeling no desire for it whatsoever, unless prompted by others. Then, through the wiles of the devil, I was so tormented by insomnia that, having remained awake for many nights, I begged God to grant me a little sleep. Thus I was in greater danger because of my immoderate fasting and insomnia than I was from gluttony and too much sleep.' Abba Moses so cheered us with teaching of this kind that we could not help glorifying the Lord who grants such great wisdom to those who fear Him; for to Him belong honor and power through all the ages. Amen.