If a king wanted to take possession of his enemy's city, he would begin by cutting off the water and the food and so his enemies, dying of hunger, would submit to him. It is the same with the passions of the flesh; if a man goes about fasting and hungry the enemies of his soul grow weak.
Beware of the counsels of the evil one, if he should come in the guise of one professing truth to beguile you and lead you into deceit. Even if he should come to you as an angel of light, do not believe him or obey him: for he is apt to fascinate the faithful by the attractive semblance of truth.
God the Word, the God-Man, our Lord Jesus Christ, compares our life with a market, and the work of our life on earth He calls trading, and says to us all: Trade till I come (Luke 19:13), redeeming the time, because the days are evil (Ephesians 5:16). That is to say, make the most of your time for getting heavenly blessings through earthly goods. Earthly goods are good works done for Christ's sake and conferring on us the grace of the All-Holy Spirit.
I think it best that a man should have a little bit of all the virtues. Therefore, get up early every day and acquire the beginning of every virtue and every commandment of God. Use great patience, with fear and long-suffering, in the love of God, with all the fervor of your soul and body. Exercise great humility, bear with interior distress; be vigilant and pray often with reverence and groaning, with purity of speech and control of your eyes. When you are despised do not get angry; be at peace, and do not render evil for evil. Do not pay attention to the faults of others, and do not try to compare yourself with others, knowing you are less than every created thing. Renounce everything material and that which is of the flesh. Live by the cross, in warfare, in poverty of spirit, in voluntary spiritual asceticism, in fasting, penitence and tears, in discernment, in purity of soul, taking hold of that which is good. Do your work in peace. Persevere in keeping vigil, in hunger and thirst, in cold and nakedness, and in sufferings. Shut yourself in a tomb as though you were already dead, so that at all times you will think death is near.
Those who have truly decided to serve the Lord God must train themselves in the remembrance of God and in unceasing prayer to Jesus Christ, saying mentally: 'Lord Jesus Christ, Son of God, have mercy on me, a sinner.' Through such activity, and by guarding oneself from distraction, and with the preservation of peace in one's conscience, it is possible to draw near to God and to be united with Him. For, according to the words of St. Isaac the Syrian, 'Except for unceasing prayer we cannot draw near to God.'
The lower you descend, the higher you ascend; and when, like the psalmist, you regard yourself as nothing before the Lord (cf. Ps. 39:5), then imperceptibly you will grow great. And when you begin to realize that you have nothing and know nothing, then you will become rich in the Lord through the practice of the virtues and spiritual knowledge.
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.'
Do not neglect the practice of the virtues; if you do, your spiritual knowledge will decrease, and when famine occurs you will go down into Egypt (Genesis 41:57, 46:6).