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.
When the door of steam baths is continually left open, the heat inside rapidly escapes through it; likewise the soul in its desire to say many things, dissipates the remembrance of God through the door of speech, even though everything it says may be good. Ideas of value always shun verbosity, being foreign to confusion and fantasy. Timely silence, then, is precious, for it is nothing less than the mother of the wisest thoughts.
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.
Let us have recourse to humility on all occasions; for the humble lie prone on the ground, and how can a man fall if he lies on the ground? But a man who stands on a height can easily fall.
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.
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).
Abba Ammonas came one day to eat in a place where there was a monk of evil repute. Now it happened that a woman came and entered the cell of the brother of evil reputation. The dwellers in that place, having learnt this, were troubled and gathered together to chase the brother from his cell. Knowing that Bishop Ammonas was in the place, they asked him to join them. When the brother in question learnt this, he hid the woman in a large cask. The crowd of monks came to the place. Now Abba Ammonas saw the position clearly but for the sake of God he kept the secret; he entered, seated himself on the cask and commanded the cell to be searched. Then when the monks had searched everywhere without finding the woman, Abba Ammonas said, 'What is this? May God forgive you!' After praying, he made everyone go out, then taking the brother by the hand he said, 'Brother, be on your guard.' With these words, he withdrew.
'Grace always precedes temptations.' He knew that grace always precedes temptations as a forewarning preparation. As soon as you perceive grace, gird yourself and say: 'Here comes the call to battle! Beware, attend, O Clay, to where the wicked on will strike the battle. Many times it comes quickly, and many times after two or three days. In any event, it will come, and the earthworks must be firm. Confessions every evening, Obedience to the elder, humility and love towards all. By these means lighten the affliction.' Grace is divided into three stages: purifying, enlightening, and perfecting. So also are deeds: natural, supernatural, contranatural. According to these three stages on ascends and descends. The great gifts one receives are also three: contemplation, love, dispassion.
When you intend to do something and see that your thought is perturbed, and if after invoking God's Name it remains perturbed even by a hair's breadth, know from this that the action you mean to commit is from the evil one and refrain from commiting it. For nothing done with perturbation is pleasing to God.
Acquire humility, which scorches the demons, obedience, which opens the door for the Son of God to enter a man, faith which saves a man, hope which makes him unashamed; and love which lets not a man fall away from God.
If we fervently desire holiness, the Holy Spirit at the outset gives the soul a full and conscious taste of God’s sweetness, so that the intellect will know exactly of what the final reward of the spiritual life consists.
As wax cannot take the imprint of a seal unless it is warmed or softened thoroughly, so a man cannot receive the seal of God's holiness unless he is tested by labors and weaknesses. That is why the Lord says to St. Paul: 'My grace is sufficient for you: for My power comes to its fullness in your weakness'; and the Apostle himself proudly declares: 'Most gladly therefore will I rather glory in my weaknesses, so that the power of Christ may rest upon me' (2 Cor. 12:9).
Watch constantly, learning to understand God's law, for this warms the heart with heavenly fire. Guard your lips from the idle word, or empty talk, lest the heart gets used to evil words.
Silence of lips is better and more wonderful than any edifying conversation. Strive to acquire humility and submissiveness. Never insist that anything should be according to your will, for this gives birth to anger. Do not judge or humiliate anyone, for this gives birth to anger. Do not judge or humiliate anyone, for this exhausts the heart and blinds the mind, and thereon leads to negligence and makes the heart unfeeling.
What is self-justification? - Self-justification is when a man denies his sin, as we see in the case of Adam, Eve, Cain and others who have sinned but, wishing to justify themselves, denied their sin.
To wage war only with the sins that make their appearance as actual deeds would be just as unsuccessful as cutting down weeds in a garden instead of digging them up at the root and throwing them out. Sins appear as inevitable outgrowths from their roots, the passions of the soul.