The deadly wound consists of every sin that is not repented and confessed, and of falling into despair. This depends on our choice and will. If we do not yield ourselves to the pit of carelessness and despair the devils cannot prevail over us. Even when we have been wounded, if we so wish we may through fervent penitence become more courageous and skillful fighters.
Whenever we are filled with evil thoughts, we should throw the invocation of our Lord Jesus Christ in their midst. Then, as experience has taught us, we shall see them instantly dispersed like smoke in air. Once the intellect is left to itself again, we can renew our constant attentiveness and our invocation. Whenever we are distracted, we should act in this way.
As earth thrown over it extinguishes a fire burning in a stove, so worldly cares and every kind of attachment to something, however small and insignificant, destroy the warmth of the heart which was there at first.
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.
Take care never to receive Communion while you have anything against anyone, even if this is only a hostile thought. Not until you have brought about reconciliation through repentance should you communicate, [receive the Mysteries]. But you will learn this, too, through prayer.
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.
We should look upon every believer alike, and suppose that Christ abides in each; we must have such loving disposition towards him as to be ready to lay down our life for him. We should never think or say that someone is evil, but, as is said, should see everyone as good. If you see someone attacked by the passions, hate not the brother but the passions attacking him.
A house roof is held up by the foundations and the rest of the building, and the foundations with the rest of the building are laid to hold the roof - since both are necessary and useful - and neither is the roof built without the foundations and the rest of the house, nor can foundations and walls without a roof make a building fit to live in. So it is with the soul: the grace of the Holy Spirit is preserved by keeping the commandments, and the keeping of commandments is the foundation laid for receiving the gift of God's grace. Neither does the grace of the Holy Spirit remain in us without our obeying the commandments, nor can obeying the commandments be useful and salutary without Divine grace.
No man, wise in his own opinion, because he has studied all the sciences and is learned in external wisdom, will ever penetrate God's mysteries or see them unless he first humbles himself and becomes foolish in his heart, repudiating his self-opinion together with his acquirements of learning. For a man who acts thus and follows with undaunted faith those who are wise in things Divine, is guided by them and with them enters into the city of the living God, and, taught and enlightened by the Holy Spirit, sees and knows things which no one else can see or know. Thus he becomes taught of God.
A man standing on the seashore sees the immense expanse of water, but his eye can embrace only a small part and cannot reach its limit. In the same way, a man who, through contemplation, is given to see the limitless ocean of Divine glory and to see God Himself with the eyes of his mind, sees God and the infinite vastness of His glory, though not the whole as it really is, but only as much as is possible for him.
'Fear of the Lord is the beginning of wisdom' (Prov. 1:7). For where there is fear, there the commandments are kept, and where the commandments are kept the flesh is purified, together with the cloud that envelops the soul and prevents it from clearly seeing the divine radiance.
Continuity of attention produces inner stability; inner stability produces a natural intensification of watchfulness; and this intensification gradually and in due measure gives contemplative insight into spiritual warfare. This in its turn is succeeded by persistence in the Jesus Prayer and by the state that Jesus confers, in which the intellect, free from all images, enjoys complete quietude.
Therefore with your whole soul you should acknowledge yourself as worthy of enduring more than you already endure; remember the words which Christ the Savior spoke concerning a good deed done to one's neighbor, words which should apply equally to every offensive word or deed against one's neighbor. Whatever you have done to your neighbor, He says, you have done to Me.