Then God will give you great strength and joy, and all godly works will become for you as sweet as honey, and all physical labours, mental occupations and vigils, generally the whole yoke of God, will be sweet and light for you. But, by struggling and prevailing, they gradually become stronger and stronger. Purity, everlasting and unchanging peace, fullness of mercy and other beautiful virtues, crowned by blessing, are God's commandments. Perfection is born of purity of heart. The heart contains good naturally and evil unnaturally.
Evil gives birth to passions of the soul, such as condemnation, hatred, vainglory and the like.
The good gives birth to knowledge of God and sanctity or purity of soul from all passions. Many who have long been monks and virgins have not learned to master this science of purity, because, disdaining the directions of their fathers, they have followed the desires of their own hearts. For this reason evil soul-destroying spirits have taken possession of them, wounding them day and night with invisible arrows and giving them no peace in any place, so that their hearts were occupied now by pride, now by vanity, now by impious envy, now by censure, now by anger and rage, now by quarrels and many other passions. Let us awake from sleep, while we are still in the body, let us sign over ourselves and mourn over ourselves from our whole heart day and night, to be delivered from the terrible torment, groaning, weeping and anguish which will have no end. Those who follow the latter way are real doers, who receive the reward of their labours with joy and inherit the kingdom.