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.
I suppose that it is sometimes better to fall oneself and rise, than to judge one's neighbor; because one who has sinned is incited to self-abasement and repentance, while he who judges one who has sinned becomes hardened in an illusion about himself and in pride. Therefore everyone must guard himself, as much as possible, so as not to judge.
One should nourish the soul with the word of God: for the word of God, as St. Gregory the Theologian says, is angelic bread, by which are nourished souls who hunger for God. Most of all, one should occupy oneself with reading the New Testament and the Psalter, which one should do standing up. From this there occurs an enlightenment in the mind, which is in the mind, which is changed by a Divine change.
We firmly believe that the Church will never fall, will never waiver and will not be destroyed. For this is what Christ taught, by Whom the heavens were established and the earth was founded, and stands firmly as the Holy Spirit says” (Ps. 32:6). The Antichrist will lure to himself 'those who have a weak and feeble mind, will seduce and will tear them away from the living God.'
That is why the Mother of God is called the ‘Scourge of Demons,’ for it is not possible for a devil to destroy a man so long as the man himself does not refrain from running to the help of the Mother of God.
It was fitting that she, who had kept her virginity intact in childbirth, should keep her own body free from all corruption even after death. It was fitting that she, who had carried the Creator as a child at her breast, should dwell in the divine tabernacles. It was fitting that the spouse, whom the Father had taken to himself, should live in the divine mansions. It was fitting that she, who had seen her Son upon the cross and who had thereby received into her heart the sword of sorrow which she had escaped when giving birth to him, should look upon Him as he sits with the Father, It was fitting that God's Mother should possess what belongs to her Son, and that she should be honored by every creature as the Mother and as the handmaid of God.
God, the Word, made man for the salvation of our race, aware of the exceeding frailty and misery of our nature, hath not even here suffered our sickness to be without remedy. But like a skillful doctor, he hath mixed for our unsteady and sin loving heart the potion of repentance, prescribing this for the remission of sins. For after we have received the knowledge of the truth, and have been sanctified by water and the Spirit, and cleansed without effort from all sin and all defilement, if we should happen to fall into any transgression, there is, it is true, no second regeneration made within us by the Spirit through baptism in the water of the font, and wholly recreating us (that gift is given once for all); but, by means of painful repentance, hot tears, toils and sweats, there is a purifying and pardoning of our offences through the tender mercy of our God. For the fount of tears is also called baptism, according to the grace of the Master.
As therefore the Lord does nothing without the Father, for says He, 'I can of mine own self do nothing,' so do you, neither presbyter, nor deacon, nor layman, do anything without the bishop.
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.'
Peace of soul is acquired by perfect surrender to the Divine Will, without which nothing happens... He, in whose heart humility and meekness are reborn, will find true rest for his soul. He will be satisfied with everything, grateful for everything, peaceful and full of love for everybody. He will judge none and will feel no anger. His heart will be filled with divine sweetness, that is, he will feel in himself the Kingdom of God because God grants His grace only to the humble.
Let us go forward with the heart completely attentive and the soul fully conscious. For if attentiveness and prayer are daily joined together, they become like Elias' fire-bearing chariot, raising us to heaven. What do I mean? A spiritual heaven, with sun, moon and stars, is formed in the blessed heart of one who has reach a state of watchfulness, or who strives to attain it.
God rests in holy places; that is (in) the Theotokos and all the Saints. These are they who have become likenesses of God as far as it is possible, since they have chosen to cooperate with divine election. Therefore, God dwells in them.
We must vigilantly guard our heart from unfitting thoughts and impressions, according to the word of the writer of Proverbs: ‘Keep thine heart with the utmost care; for out of these are the issues of life,’ (Proverbs 4:23).
A brother who shared a lodging with other brothers asked Abba Bessarion, 'What should I do?' The old man replied, 'Keep silence and do not compare yourself with others.'
God's all-saving will consists in doing good solely to acquire the Holy Spirit, as an eternal, inexhaustible treasure which cannot be rightly valued... This is the oil in the lamps of the wise virgins which could burn long and brightly, and these virgins with their burning lamps were able to meet the Bridegroom Who came at midnight, and could enter the bridechamber of joy with Him. But the foolish ones, though they went to market to buy some oil when they saw their lamps going out, were unable to return in time, for the door was already shut. The market is our life; the door of the bridechamber which was shut and which barred the way to the Bridegroom is human death; the wise and foolish virgins are Christian souls; the oil is not good deeds but the grace of the All-Holy Spirit of God which is obtained through them and which changes souls from one state to another - that is, from corruption to incorruption, from spiritual death to spiritual life, from darkness to light, from the stable of our being (where the passions are tied up like dumb animals and wild beasts) into a temple of the Divinity, into the shining bridechamber of eternal joy in Christ Jesus our Lord, the Creator and Redeemer and eternal Bridegroom of our souls.
One must endeavor to read through the writings of the Fathers, and strive as much as possible, according to one’s strength, to fulfill what they teach, and in this fashion, little by little ascend from the ascetic life to the perfection of the contemplative.