It's difficult to be saved in the world amidst the seductions and the customs of this world that go counter to the Holy Church. Evil communications corrupt good manners (I Cor. 15:33). It's difficult to be saved in the midst of dissolute society. In the Holy Scriptures it is said, With the holy man wilt thou be holy, and with the innocent man wilt thou be innocent. And with the elect man wilt thou be elect, and with the perverse wilt thou be perverse (Ps. 17:25-6).
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.
St. Paul says: 'The person engaged in spiritual warfare exercises self control in all things' (I Cor. 9:25). Aware of all that is said in divine Scripture, let us lead our life with self-control, especially in regard to food.
Apostolic teaching, Beloved, exhorts us that we put off the old man with his deeds (Eph. iv. 22; Col. iii. 9), and renew ourselves from day to day by a holy manner of life. For if we are the temple of God, and if the Holy Spirit is a Dweller in our souls, as the Apostle says: You are the temple of the living God (II Cor. vi. 16); we must then strive with all vigilance that the dwelling of our heart be not unworthy of so great a Guest.
You know that evil entered into us through the transgression of the commandments. Hence it is obvious that by keeping them, evil departs from us. But without the doing of the commandments we should not even aspire or hope for purity of soul, because at the very outset we do not walk on the path that leads us to purity of soul. Do not say that God can give us the grace of purity of soul even without our keeping the commandments.
Nothing is more unsettling than talkativeness and more pernicious than an unbridled tongue, disruptive as it is of the soul’s proper state. For the soul’s chatter destroys what we build each day and scatters what we have laboriously gathered together.
How can one say that a man has attained purity? - When he sees all men as being good, and when none appears to him to be unclean and defiled - then he is indeed pure in heart.
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.
It is just as shameful for lovers of the flesh and the belly to search out spiritual things as it is for a harlot to discourse on chastity. A body suffering grave illness shuns fatty foods and abhors them; and likewise, a mind occupied with worldly affairs cannot approach the inquiry into things of God. A fire cannot be ignited with wet wood, nor can the divine fervor be kindled in a heart that loves ease.