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.
Temptations are sent for improvement when God delivers his righteous ones to various temptations, humiliating them for some slight and unimportant offense, or to increase their purity, in order that every uncleanliness of thought, or... dross which He sees they have harbored in secret, may be burnt away in this present life, and that so He may bring them, as it were pure gold, to the future judgment...
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.
That prayer may be poured forth with that fervor and singleness of heart that it ought to have, these rules must always be observed. In the first place, anxiety concerning the things of the flesh must be altogether be put away; then we must not allow to enter our minds any thought or even memory of worldly cares or business. We must cut off slanderings, vain words or many words, jestings and the like. We must root out the disturbances of anger especially, and despondency, and also tear up the
evil roots of carnal lust and avarice. And so with these and similar faults done entirely away with and cut off, - things which can also be discerned by human eyes - and with such a cleansing and purifying as we have mentioned first carried out in the sincerity of simplicity and innocence, we must lay the unshakable foundations of humility strong enough to sustain a tower which shall pierce the heavens.
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.
Condemn only yourself, and you will not be condemned at His second and awful coming. From your whole heart remit the sins of whoever sins before you, and your Father who is in heaven will remit your sins.
A small affliction borne for God's sake is better [before God] than a great work performed without tribulation, because affliction willingly borne brings to light the proof of love.
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).
God often permits virtuous men to be tried by something: He permits temptations to rise up against them on all sides... Whether these trials come from men, demons or flesh, let it be a cause for thanksgiving. For God cannot show his favor to a man who desires to dwell with Him, except by sending him trials for the sake of truth; just as no man can become worthy of this greatness... without the grace of Christ... St. Paul plainly calls it a gift... 'For unto you it is given in behalf of Christ, not only to believe in Him, but also to suffer for His sake' (Phil. 1:29).
A worker takes the trouble to get hold of the instruments that he requires. He does so not simply to have them and not use them. Nor is there any profit for him in merely possessing the instruments. What he wants is, with their help, to produce the crafted objective for which these are the efficient means. In the same way, fasting, vigils, scriptural meditation, nakedness and total deprivation do not constitute perfection but are the means to perfection. They are not in themselves the end point of a discipline, but an end is attained to through them.