Not every man can be trusted when giving advice to those who seek it. We can trust only him who has received from God the grace of discrimination and who ... has acquired through great humility and long practice of the virtues an intellect blessed with spiritual insight. Such a man is in a position to advise, not everyone, but at least those who seek him out voluntarily and who question him by their own choice; for he has learned things in their true order.
Those who meditate unceasingly upon the holy and glorious name [of Jesus] in the depths of their heart can sometimes see the radiance of their own spirit-intelligence. For when the mind is profoundly concentrated on this invocation, we feel experientially how it starts burning off all the layers of dirt that normally suffocates the soul.
When the enemy tempts you with thoughts of faithlessness, with all your heart say, I believe completely whatever the Church believes, whatever Christ says in the Holy Gospels, whatever the Holy Apostles and the Holy Fathers said. 'I don't, however, believe you, devil, for you are a liar and a thief.'
Remember, O my soul, the terrible and frightful wonder: that your Creator for your sake became Man, and deigned to suffer for the sake of your salvation. His angels tremble, the Cherubim are terrified, the Seraphim are in fear, and all the heavenly powers ceaselessly give praise; and you, unfortunate soul, remain in laziness. At least from this time forth arise and do not put off, my beloved soul, holy repentence, contrition of heart and penance for your sins.
Such are the souls of the saints: they love their enemies more than themselves, and in this age and in the age to come they put their neighbor first in all things, even though because of his ill-will he may be their enemy.
Even a pious person is not immune to spiritual sickness if he does not have a wise guide -- either a living person or a spiritual writer. This sickness is called prelest, or spiritual delusion, imagining oneself to be near to God and to the realm of the divine and supernatural. Even zealous ascetics in monasteries are sometimes subject to this delusion, but of course, laymen who are zealous in external struggles (podvigi) undergo it much more frequently. Surpassing their acquaintances in struggles of prayer and fasting, they imagine that they are seers of divine visions, or at least of dreams inspired by grace. In every event of their lives, they see special intentional directions from God or their guardian angel. And then they start imagining that they are God's elect, and often try to foretell the future. The Holy Fathers armed themselves against nothing so fiercely as against this sickness -- prelest.
What should one do so that the mind might be constantly occupied with God? If we do not acquire the three following virtues: love for God and men, continence, and the Prayer of Jesus, then our mind cannot be completely occupied with God. For love makes anger meek, continence weakens fleshly desire, and prayer draws the mind away from thoughts and banishes every hatred and high-mindedness.
Therefore, if you wish to conquer the passions, cut off the love of pleasure; but if you are pursuing food, you will spend a life in passions; the soul will not be humbled if the flesh is not deprived of bread. It is not possible to deliver the soul from perdition while protecting the body from unpleasantness.
When we fervently remember God, we feel divine longing well up within us from the depths of our heart. The evil spirits invade and lurk in the bodily senses, acting through the compliancy of the flesh upon those still immature in soul. According to the Apostle, our intellect always delights in the laws of the Spirit (cf. Rom. 7:22), while the organs of the flesh allow themselves to be seduced by enticing pleasures. Furthermore, in those who are advancing in spiritual knowledge, grace brings an ineffable joy to their body through the perceptive faculty of the intellect. But the demons capture the soul by violence through the bodily senses, especially when they find us faint-hearted in pursuing the spiritual path. They are, indeed, murderers provoking the soul to what it does not want.
Such are the souls of the saints: they love their enemies more than themselves, and in this age and in the age to come they put their neighbor first in all things, even though because of his ill-will he may be their enemy.
He who is afraid of God's punishment has a slave-like fear of God, and it is this that makes him refrain from evil: 'Out of fear of the Lord men shun evil' (Prov. 16:6. LXX)... through fear of what threatens us we sinners may be led to repent and may seek deliverance from our sins...The more a man struggles to do good, the more fear grows in him, until it shows him his slightest faults, those which he thought of as nothing while he was still in the darkness of ignorance. When fear in this way has become perfect, he himself becomes perfect through inward grief: he no longer desires to sin but, fearing the return of the passions, he remains in this pure fear invulnerable. As the psalm puts it, 'The fear of the Lord is pure, and endures for ever' (Ps. 19:9. LXX). The first kind of fear is not pure, for it arises in us because of our sins. But, independent of sin, the person who has been purified continues to feel fear, not because he sins, but because, being human, he is changeable and prone to evil. In his humility, the further he advances through the acquisition of the virtues, the more he fears. This is natural; for everyone who possesses wealth greatly fears loss, punishment, dishonor, and the consequent fall from his high estate...The sign of the first kind of fear is hatred of sin and anger towards it, like someone wounded by a wild beast. The sign of perfect fear is the love of virtue and the fear of relapsing, since no one is unalterable.
You have no peace from thoughts, which impel you to trouble others, and in turn to be troubled by others. But know, my brother, that if we offend by word or deed, we are thereby ourselves offended a hundredfold. Be longsuffering in all things and refrain from letting your own will enter into anything. Carefully examine your thoughts lest they infect your heart with deadly poison (ill temper) and make you take a gnat for a camel, a pebble for a cliff, and lest you become like a man who has a beam in his own eye but beholds the mote in the eye of another.
To those who are just beginning to long for holiness, the path of virtue seems very rough and forbidding. It appears like this, not because it really is difficult, but because our human nature from the womb is accustomed to the wide roads of sensual pleasure. But those who have traveled more than half its length find the path of virtue smooth and easy. For when a bad habit has been subjected to a good one through the energy of grace it is destroyed along with the remembrance of mindless pleasures; and thereafter the soul gladly journeys on all the ways of virtue. At the beginning of the struggle, therefore, the holy commandments of God must be fulfilled with a certain forcefulness of will (cf. Matt. 11:12); then the Lord, seeing our intention and labor, will grant us readiness of will and gladness in obeying His purpose. For 'it is the Lord who makes ready the will' (Prov. 8:35, LXX), so that we always do what is right joyfully. Then shall we truly feel that 'it is God who energizes in you both the willing and the doing of His purpose' (Phil. 2:13).