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).
Pray before your body takes rest on your bed... If you are tempted, make the Sign (of the Cross) on your forehead reverently… for this is a known and tested weapon against the Devil.
'Lord Jesus Christ, Son of God, have mercy on me, a sinner.' Let your attention and instruction be centered on this. Walking, eating, standing in church before the beginning of the service, continue with the prayer; on entering and departing keep this prayer on your lips and within your heart. In such a manner, with the invocation of the Name of God you will find peace, you will attain to purity of spirit and body; and the Holy Spirit, the Origin of all good, will make for Himself a dwelling within you and will guide you in all piety and purity.
Watchfulness cleanses the conscience and makes it lucid. Thus cleansed, it immediately shines like a light that has been uncovered, banishing such darkness. Once this darkness has been banished through constant and genuine watchfulness, the conscience then reveals things hidden from us.
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.
'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.
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.
Concerning the fault of our brother, seeing and hearing of it, be toward it as a blind man, deaf man, and dumb one, not seeing, not hearing, and not speaking, as one crude of mind, not understanding, not showing oneself to be wise. But to oneself be attentive, discerning, and clear-sighted.
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.'
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.
The body is a slave, the soul a sovereign, and therefore it is due to Divine mercy when the body is worn out by illness: for thereby the passions are weakened, and a man comes to himself; indeed, bodily illness itself is sometimes caused by the passions.
In no art do the artists judge the result of their work by the tools they use, but they await the work's completion and by it judge the art. Adopting such a practice with regard to food, not placing all your hope on fasting, but fasting moderately and according to the amount of your strength, strive toward mental activity. In this way you can avoid pride and will not spurn God's good works, sending up praises to God for everything.
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.
Reprimand without feeding thine own self-love, considering whether thou wouldst be able to bear what thou demandest of another... It is of greater benefit for the soul to acknowledge itself to be guilty of everything and the last of all, than to resort to self-justification, which hath its origin in pride: God opposeth the prideful, but giveth grace unto the humble.