Because of the Fall of man, the natural order of things has become chaotic. In nature, there is an order for all things, but with man there is chaos, Everything is distorted and turned around. Because of our disobedience to the commandments of our Heavenly Father, we have lost the natural order. In order to reestablish this order, we must practice abstinence.
“But nothing causes such exceeding grief as when anyone, lying under the captivity of sin, calls to mind from where he has fallen, because he turned aside to carnal and earthly things, instead of directing his mind in the beautiful ways of the knowledge of God. So you find Adam concealing himself, when he knew that God was present and wishing to be hidden when called by God with that voice which wounded the soul of him yourself? Why are you concealed? Why do you avoid Him Whom you once longed to see? A guilty conscience is so burdensome that it punishes itself without a judge, and wishes for covering, and yet is bare before God.”
+ St. Ambrose Milan, Concerning Repentance, Book II
“Beware of self-delusion! Beware of the deceptions of the enemy! Do not think that a man is a real scholar of the Bible because he can quote by memory ever so many passages. Did not the first one who fell from the most elevated condition into the lowest hell, did not Satan know the Word of God? Yea, before it was written into a book by human hand. Look and see how the Devil quotes from the Bible when he tempted the Lord in the wilderness, and said: ‘He shall give His angels charge over thee, to keep thee in all thy ways. They shall bear thee up in their hands, lest thou dash thy foot against a stone.’ [Psalm 90:11-12 LXX] The Devil withheld the words that follow immediately after these, which read: “Thou shalt tread upon the lion and adder; the young lion and the dragon shalt thou trample under foot.’ [Psalm 90:13 LXX]”
As man I deliberately transgressed the divine commandment, when the devil, enticing me with the hope of divinity (cf. Gen. 3:5), dragged me down from my natural stability into the realm of sensual pleasure; and he was proud to have thus brought death into existence, for he delights in the corruption of human nature. Because of this, God became perfect man, taking on everything that belongs to human nature except sin (cf. Heb. 4:15); and indeed sin is not part of human nature, In this way, by enticing the insatiable serpent with the bait of the flesh. He provoked him to open his mouth and swallow it. This flesh proved poison to him, destroying him utterly by the power of the Divinity within it; but to human nature it proved a remedy restoring it to its original grace by that same power of the Divinity within it. For just as the devil poured out his venom of sin on the tree of knowledge and corrupted human nature once it had tasted it, so when he wished to devour the flesh of the Master he was himself destroyed by the power of the Divinity within it.
“The Most High planted in the middle of Paradise The thrice blessed wood, the gift of life for us, In order that, in approaching it, Adam might find eternal and immortal life, But he did not strive earnestly to know this life, And he failed to attain it, and revealed death. However, the robber, seeing how the plant in Eden Had been beautifully transplanted in Golgotha, Recognized the life in it and said to himself: `This is what my father lost formerly In Paradise.'”
+ St. Romanos the Melodist, On the Adoration at the Cross
Through greed we underwent the first stripping, overcome by the bitter tasting of the fruit, and we became exiles from God. But let us turn back to repentance and, fasting from the food that gives us pleasure, let us cleanse our senses on which the enemy makes war. Let us strengthen our hearts with the hope of grace, and not with foods which brought no benefit to those who trusted in them. Our food shall be the Lamb of God, on the holy and radiant night of His Awakening: the Victim offered for us, given in communion to the disciples on the evening of the Mystery, who disperses the darkness of ignorance by the Light of His Resurrection.
— Aposticha, Vespers on the evening of the Sunday of the Last Judgement, Lenten Triodion, p. 166