And so I remember that while I was still a boy, in the region of Thebaid, where the blessed Antony lived, the elders came to him to inquire about perfection: and though the conference lasted from evening till morning, the greatest part of the night was taken up with this question.
For it was discussed at great length what virtue or observance could preserve a monk always unharmed by the snares and deceits of the devil, and carry him forward on a sure and right path, and with firm step to the heights of perfection.
And when each one gave his opinion according to the bent of his own mind, and some made it consist in zeal in fasting and vigils, …. others in despising all things, … others thought that withdrawal from the world was the thing needful, … others laid down that the duties of charity, i.e., of kindness should be practiced, … and when in this fashion they declared that by means of different virtues a more certain approach to God could be secured, …. then at last the blessed Antony spoke and said:
All these things which you have mentioned are indeed needful, and helpful to those who are thirsting for God, and desirous to approach Him. But countless accidents and the experience of many people will not allow us to make the most important of gifts consist in them.
For often when men are most strict in fasting or in vigils, and nobly withdraw into solitude, and aim at depriving themselves of all their goods so absolutely that they do not suffer even a day’s allowance of food or a single penny to remain to them, and when they fulfill all the duties of kindness with the utmost devotion, yet still we have seen them suddenly deceived, so that they could not bring the work they had entered upon to a suitable close, but brought their exalted fervor and praiseworthy manner of life to a terrible end.
Wherefore we shall be able clearly to recognize what it is which mainly leads to God, if we trace out with greater care the reason of their downfall and deception. For when the works of the above mentioned virtues were abounding in them, discretion alone was wanting, and allowed them not to continue even to the end.
Nor can any other reason for their falling off be discovered except that as they were not sufficiently instructed by their elders they could not obtain judgment and discretion, which passing by excess on either side, teaches a monk always to walk along the royal road, and does not suffer him to be puffed up on the right hand of virtue, i.e., from excess of zeal to transgress the bounds of due moderation in foolish presumption, nor allows him to be enamored of slackness and turn aside to the vices on the left hand, i.e., under pretext of controlling the body, to grow slack with the opposite spirit of lukewarmness.
For this is discretion, which is termed in the gospel the “eye,” “and light of the body,” according to the Savior’s saying: “The light of thy body is thine eye: but if thine eye be single, thy whole body will be full of light, but if thine eye be evil, thy whole body will be full of darkness:” (Mat 6:22,23) because as it discerns all the thoughts and actions of men, it sees and overlooks all things which should be done. But if in any man this is “evil,” i.e., not fortified by sound judgment and knowledge, or deceived by some error and presumption, it will make our whole body “full of darkness,” i.e., it will darken all our mental vision and our actions, as they will be involved in the darkness of vices and the gloom of disturbances.
For, says He, “if the light which is in thee be darkness, how great will that darkness be!” For no one can doubt that when the judgment of our heart goes wrong, and is overwhelmed by the night of ignorance, our thoughts and deeds, which are the result of deliberation and discretion, must be involved in the darkness of still greater sins.
Cassian’s Conferences, 2nd Conference of Abbot Moses, Chapter 2, NPNF 2nd series, Vol.11, p.308.