When a man gives God his secret things, that is, his mind and thoughts, not occupying himself elsewhere, nor wandering away, but putting constraint upon himself, then the Lord deems him worthy of mysteries, in greater sanctity and purity, and gives him heavenly food and spiritual drink
In order to preserve the mind and body in a perfect condition abstinence from food is not alone sufficient: unless the other virtues of the mind as well are joined to it. And so humility must first be learned by the virtue of obedience, and grinding toil and bodily exhaustion. The madness of anger should be controlled; the downcast look of dejection be overcome; vainglory should be despised, the disdainfulness of pride trampled under foot, and the shifting and wandering thoughts of the mind restrained by continual recollection of God. And the slippery wanderings of our heart should be brought back again to the contemplation of God as often as our crafty enemy, in his endeavour to lead away the mind a captive from this consideration, creeps into the innermost recesses of the heart.
Many are the obstacles that stand in the way of pleasing God; for not merely poverty and obscurity but also riches and honor are trials for the soul. Indeed, to some extent even the solace and ease which grace bestows on the soul can easily become a temptation and a hindrance if the soul is not properly conscious of these effects of grace and does not enjoy them with great circumspection and understanding: for the spirit of evil tries to persuade the soul to relax now it possesses grace, and so contrives to implant in it sluggishness and apathy.
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.
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.
What can God do with one who willfully gives himself over to the world, and is deceived by its pleasures, or led astray by material wanderings? The man to whom He gives help is the one who turns away from material pleasures and from his former habits, who drags his mind at all times to the Lord, whether it will or not, who denies himself and seeks the Lord only. This is the man whom He keeps under His care: who guards himself on every side from the snares and entanglements of the material world, who works out his own salvation with fear and trembling, who passes with all heed amidst the snares and entanglements and lusts of this world, and seeks the help of the Lord, and hopes by His mercy to be saved through grace.
We must with unflagging zeal and care give ourselves to the pursuit of virtue, and constantly occupy ourselves in its practice, lest at any time progress may cease, and regress immediately take its place.... To cease to acquire means to lose, for the will which goes no longer forward will not be far from peril of falling back.
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...
If a man purifies his heart and uproots from it all sin against the Lord; if he labors diligently to acquire Divine knowledge and succeeds in seeing with his mind that which is invisible to many, he must not through this exalt himself over others. Who among creatures is purer than an incorporeal being and who has more knowledge than an Angel? Yet, having exalted himself he was cast down from heaven like lightning. His pride was regarded by God as impurity.