If you believe in a Divine Providence which determines the earthly fate of everyone and the way by which he is to be saved, you must also believe that the disposition of your life is the most suitable for you in working out your salvation.
Observe your thoughts, and beware of what you have in your heart and your spirit, knowing that the demons put ideas into you so as to corrupt your soul by making it think of that which is not right, in order to turn your spirit from the consideration of your sins and of God.
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.
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).
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.
One should not ponder divine matters on a full stomach, say the ascetics. For the well-fed, even the most superficial secrets of the Trinity lie hidden.
Fasting, while of value in itself, is not something to boast of in front of God, for it is simply a tool for training those who desire self-restraint. The ascetic should not feel proud because he fasts; no artist ever boasts that his accomplishment is simply due to his tools; but he waits for the work itself to give proof of his skill.
Fasting is acceptable to God when abstention from food is accompanied by refraining from sins, from envy, from hatred, from calumny, from vainglory, from wordiness, from other evils. He who is fasting the true fast `that is agreeable' to God ought to shun all these things with all his strength and zeal, and remain impregnable and unshakeable against all the attacks of the evil one that are planned from that quarter. On the other hand, he who practices abstention from food, but does not keep self-control in the face of the aforesaid passions, is like unto one who lays down splendid foundations for a house, yet takes serpents and scorpions and vipers as fellow-dwellers therein.
Hold faith and humility fast within you; for through them you will find mercy, help, and words spoken by God in the heart, along with a protector who stands beside you both secretly and manifestly.
Fasting is an exceptional virtue; it represses bodily impulses and gives strength to the soul to fight against the poisoning of the heart through the senses, and provides it with a remedy against any past poisoning. Fasting causes the mind to be cleansed constantly. It withers up every evil thought and brings healthy, godly thoughts -- -holy thoughts that enlighten the mind and kindle it with more zeal and spiritual fervor.
But if you are fearful of becoming self-righteous from working for your own salvation, or afraid of being overcome by spiritual pride, examine yourself and observe that the person who is afraid of becoming self-righteous suffers from blindness. For he does not see how self-righteous he is.
We must not only keep a sharp watch over our diet, but keep away from all other kinds of sin so that as our stomach keeps fast, so also may our tongue as we abstain from calumny, from deceit, from idle talk, from railing and anger and all other vices which arise from the tongue. So also let our eyes keep fast. No looking for trivialities, no letting the eyes wander freely, no impudent lying in wait for people to talk to. The same with the hands and feet, to prevent them from doing anything evil. Fasting in this way, as St. Basil says, is an acceptable fast and, leaving behind all the evil to which our senses are inclined, we may come to the holy day of Resurrection, renewed and clean and worthy to share in the Holy Mysteries.
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.
Almsgiving heals the soul's incensive power; fasting withers sensual desire; prayer purifies the intellect and prepares it for contemplation of created beings. For the Lord has given us commandments which correspond to the powers of the soul.
The partaking of food has three degrees: abstinence, adequacy and satiety. To abstain, means to remain a little hungry after eating; to eat adequately, means neither to be hungry, nor weighed down. But eating beyond satiety is the door to belly-madness, through which lust comes in. But you, firm in knowledge, choose what is best for you, according to your powers, without overstepping the limits...