Bodily purity is primarily attained through fasting, and through bodily purity comes spiritual purity. Abstinence from food, according to the words of that son of grace, St. Ephraim the Syrian, means: 'Not to desire or demand much food, either sweet or costly; to eat nothing outside the stated times; not to give oneself over to gratification of the appetite; not to stir up hunger in oneself by looking at good food; and not to desire one or another sort of food.
If a person swallows too much food, he is inviting impure thoughts. If he mortifies the stomach, he is creating pure thoughts. Often a lion if it is caressed becomes domesticated, whereas the more you coddle the body, the more it goes wild.
Suppose you have ordered yourself not to eat fish; you will find that the enemy continually makes you long to eat it. You are filled with an uncontrollable desire for the thing that is forbidden. In this way you can see how Adam's fall typifies what happens to all of us. Because he was told not to eat from a particular tree, he felt irresistibly attracted to the one thing that was forbidden him.
Fasting is the champion of every virtue, the beginning of the struggle, the crown of the abstinent, the beauty of virginity and sanctity, the resplendence of chastity, the commencement of the path of Christianity, the mother of prayer, the well-spring of sobriety and prudence, the teacher of stillness, and the precursor of all good works. Just as the enjoyment of light is coupled with healthy eyes, so desire for prayer accompanies fasting that is practiced with discernment.
Concerning fasting, do not grieve, as I have said to you before: God does not demand of anyone labors beyond his strength. And indeed, what is fasting if not a punishment of the body in order to humble a healthy body and make it infirm for passions, according to the word of the Apostle: 'When I am weak, then am I strong' (II Corinthians 12:10).
The undefiled beauty of fasting is the pure mother of character. It causes philosophy to gush forth, and offers a crown. It negotiates Paradise for us and grants a paternal family for those who fast. Of this Adam was deprived, and he attracted death, when he dishonored the worth of feasting. For at the time when it was treated scornfully, the God of all, the Creator and the Master was at once displeased. To those who honor it He grants eternal life.
Sear your loins by abstaining from food, and prove your heart by controlling your speech, and you will succeed in bringing the desiring and incensive powers of your soul into the service of what is noble and good.
Fasting is an ordinance of the Church, obliging the Christian to observe it on specific days. Concerning fasting, our Savior teaches: 'When thou fastest, anoint thine head, and wash thy face; that thou appear not unto men to fast, but unto thy Father Who is in secret: and thy Father, Who seeth in secret, shall reward thee openly.' From what the Savior teaches we learn (a) that fasting is pleasing to God, and (b) that he who fasts for the uplifting of his mind and heart towards God shall be rewarded by God, Who is a most liberal bestower of Divine gifts, for his devotion. In the New Testament fasting is recommended as a means of preparing the mind and the heart for divine worship, for long prayer, for rising from the earthly, and for spiritualization.
The Holy Fathers recommend 'moderate' fasting; one ought not to allow the body to be weakened too much, for then the soul, too, is harmed. Nor ought one to undertake fasting too suddenly; everything demands practice, and each one should look to his own nature and occupation. To choose among different kinds of food is to be condemned; all food is God-given, but it is advisable to avoid such kinds as add to the body's weight and appetite; strong spices, meat, spirituous drinks and such foods as are solely for the palate's enjoyment. For the rest, one may eat what is cheap and most easily available, they say. But by 'moderate' they mean one meal a day, and that one light enough not to fill the stomach to satiety.
In no art do the artists judge the result of their work by the tools they use, but they await the work's completion and by it judge the art. Adopting such a practice with regard to food, not placing all your hope on fasting, but fasting moderately and according to the amount of your strength, strive toward mental activity. In this way you can avoid pride and will not spurn God's good works, sending up praises to God for everything.
I shall speak first about control of the stomach, the opposite to gluttony, and about how to fast and what and how much to eat. I shall say nothing on my own account, but only what I have received from the Holy Fathers. They have not given us only a single rule for fasting or a single standard and measure for eating, because not everyone has the same strength; age, illness or delicacy of body create differences. But they have given us all a single goal: to avoid over-eating and the filling of our bellies... A clear rule for self-control handed down by the Fathers is this: stop eating while still hungry and do not continue until you are satisfied.
Once two brothers came to a certain old man. It was his custom not to eat every day but when he saw them he received them joyfully and said, 'A fast has its own reward, but he who eats for the sake of love fulfils two commandments: he leaves his own will and he refreshes his brothers.'
The old man (Abba Moses) was asked, 'What is the good of the fasts and watchings which a man imposes on himself?' and he replied, 'They make the soul humble. For it is written, ‘Consider my affliction and my trouble, and forgive all my sins’ (Psalm 25:18). So if the soul gives itself all this hardship, God will have mercy on it.'
When the intellect begins to advance in love for God, the demon of blasphemy starts to tempt it, suggesting thoughts such as no man but only the devil...could invent. He does this out of envy, so that the man of God, in his despair at thinking such thoughts, no longer dares to soar up to God in his accustomed prayer. But the demon does not further his own ends by this means. On the contrary, he makes us more steadfast. For through his attacks and our retaliation we grow more experienced and genuine in our love for God.
To what end do fasting and penitence lead? For what purpose is this trouble taken? They lead to the cleansing of the soul from sins, to peace of heart, to union with God; they fill us with devotion and sonship, and give us boldness before God.