Saint Symeon the New Theologian.
That one should not embrace and zealously observe the benefit of the fast only in the first week of Lent, but that the zealous must continue the same zeal in all the weeks of Lent.
The first week of lent.
Brethren and fathers, what we are about to say we ought to have addressed to your charity last Sunday. I was aware, however, that everyone of us believers, [together with] the whole Christian people, both monks and laity, with fervent zeal accepts the blessing of fasting in the holy first week of Lent, and that each one of us willingly puts its yoke upon his neck (Sir. 51:26). Even among those who greatly despair of their own salvation and live their lives without fear and reverence for God there is no one who rejects the law of fasting in that week. Rather, as far as he is able, he joins with all in observing abstinence. So I come today to speak a few short words to you about the present season.
As we have said, all faithful people spend the first week of Lent, which is now past, in a strenuous manner. But now that it is past and Saturday has arrived, it falls to the lot of the Church of God to celebrate, in accordance with tradition, the feast of the great martyr Saint Theodore, or rather, the extraordinary act of salvation that God wrought through him for His most faithful people. Likewise on Sunday we all make commemoration of the Orthodox Faith - and sing hymns of thanksgiving to God, who is all-good. But the evil one, who is always envious of goodness, secretly steals up on each of the faithful and invisibly puts on him the chains of slackness and carelessness. He persuades him to despise and reject the salutary yoke of fasting (cf Ps. 2:3) and to return to his former habits. Therefore I remind you today and make my appeal to your charity, your paternity, that you do not in any way obey him who wills you ill. Do not be led astray by the bad habit of insatiable gluttony, nor turn back to the old [habit of] satisfaction of evil desires. Rather, let us keep this second week of Lent like the first, and likewise the remainder [of the season].
Fasting as the healer of the soul.
Indeed, my fathers and brethren, let us act for our own good by so doing, and let us not allow ourselves to lose what we have gathered together in the past, but rather let us strive to add to it and increase it. Let us not miserably allow what we have built up in times past to be destroyed (cf Gal. 2:18). Let each one of us keep in mind the benefit of fasting and what gifts from God he has enjoyed in these few days and so become more eager for the days to come. For this healer of our souls is effective, in the case of one to quieten the fevers and impulses of the flesh, in another to assuage bad temper, in yet another to drive away sleep, in another to stir up zeal, and in yet another to restore purity of mind and to set him free from evil thoughts. In one it will control his unbridled tongue and, as it were by a bit (Jas. 3:3, 8), restrain it by the fear of God and prevent it from uttering idle or corrupt words (Eph. 4:29; Mt. 12:36). In another it will invisibly guard his eyes and fix them on high instead of allowing them to roam hither and thither, and thus cause him to look on himself and teach him to be mindful of his own faults and shortcomings. Fasting gradually disperses and drives away spiritual darkness and the veil of sin that lies on the soul, just as the sun dispels the mist. Fasting enables us spiritually to see that spiritual air in which Christ, the Sun who knows no setting, does not rise, but shines without ceasing. Fasting, aided by vigil, penetrates and softens hardness of heart. Where once were the vapors of drunkenness it causes fountains of compunction to spring forth. I beseech you, brethren, let each of us strive that this may happen in us!. Once this happens we shall readily, with God's help, cleave through the whole sea of passions and pass through the waves of the temptations inflicted by the cruel tyrant, and so come to anchor in the port of impassibility.
Fasting as the foundation of all spiritual activity.
My brethren, it is not possible for these things to come about in one day or one week!. They will take much time, labor, and pain, in accordance with each man's attitude and willingness, according to the measure of faith (Rom. 12:3, 6) and one's contempt for the objects of sight and thought. In addition, it is also in accordance with the fervor of his ceaseless penitence and its constant working in the secret chamber of his heart (Mt. 6:6) that this is accomplished more quickly or more slowly by the gift and grace of God. But without fasting no one was ever able to achieve any of these virtues or any others, for fasting is the beginning and foundation of every spiritual activity. Whatever you will build on this foundation cannot collapse or be destroyed, because they are built on solid rock. But if you remove this foundation and substitute for it a full stomach and improper desires, they will be undermined like sand by evil thoughts, and the whole structure of virtues will be destroyed (cf Mt. 7:26/; Lk. 6:49). To prevent this from happening in our case, my brethren, let us gladly stand on the solid foundation of fasting. Let us stand firmly, let us stand willingly!... He who is compelled to climb the rock of fasting against his will cannot fail to be dragged down by his desire and thrown headlong into eating in secret. And so, as he nibbles, he becomes, I think, food for the evil one, for fasting is a divine law and those who presume to transgress it are seized by the devil, who flogs them like an executioner. If this does not happen immediately or quickly it is because God is patient with us and accepts our penitence. Yet we shall not altogether "escape his hand" (Tb. 13:2) either in this life or in the world to come, if we persist in sin without repenting thereof. If we act in this way we shall share in the devil's condemnation and at his hand and together with him we shall receive eternal punishments by the just judgment of God. We may be hidden from our superiors, yet we cannot be hidden from the Master and God of our superiors.
Reference:
deCatanzaro C.J. (1980), Symeon the New Theologian: The Discourses, Paulist Press, New Jersey, Unites States of America.