It is impossible for the soul to attain anything spiritual and pleasing to God, or to be free of inner sin, without guarding of the mind and purity of heart, in other words, without sobriety... If with God's help we gain something daily through our sobriety, we should take care not to enter into communication with other people without discrimination, lest we suffer loss through our converse with them and are led into temptation.
Read often and insatiably the books of the teachers of the Church on divine providence, for they lead the mind to discern the order in God’s creatures and His actions, give it strength, and by their subtleness they prepare it to acquire luminous intuitions and guide it in purity toward understanding of God’s creatures. Read also the Gospels, which God ordained for knowledge for the whole world, that you may find provisions for your journey in the might of God’s providence for every generation, and that your intellect may plunge deeply into wonder at Him. Such reading furthers your aim. Let your reading be done in a stillness which nothing disturbs; be free of all concern for the body and the turmoil of affairs, so that through the sweet understanding which surpasses all the senses you may savor that most sweet taste in your soul which she perceives in herself because of her constant intercourse with these things.
The cross is the door to mysteries. Through this door the intellect makes entrance in to the knowledge of heavenly mysteries. The knowledge of the cross is concealed in the sufferings of the cross. And the more our participation in its sufferings, the greater the perception we gain through the cross. For, as the Apostle says, `As the sufferings of Christ abound in us, so our consolation also aboundeth by Christ.'
Watchfulness and the Jesus Prayer, as I have said, mutually reinforce each other, for close attentiveness goes with constant prayer, while prayer goes with close watchfulness and attentiveness of intellect.
As a man whose head is under water cannot inhale pure air, so a man whose thoughts are plunged into the cares of this world cannot absorb the sensations of that new world.
Whenever we are filled with evil thoughts, we should throw the invocation of our Lord Jesus Christ in their midst. Then, as experience has taught us, we shall see them instantly dispersed like smoke in air. Once the intellect is left to itself again, we can renew our constant attentiveness and our invocation. Whenever we are distracted, we should act in this way.
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.
It is impossible for the soul to be liberated from turbulent thoughts without the virtue of non-possessiveness. And without peace of the bodily senses it is impossible for the soul to have a peaceful intellect. And if it does not come into temptations it will not acquire wisdom of the Holy Spirit. And without laborious and persistence in reading, it will not come to the discernment of thoughts. And without the stillness of thoughts, the intellect cannot move to seek the hidden mysteries of God.
But if you give a strong body rest and ease and idleness, all the passions dwelling in the soul are intensified. Then, even if the soul has a great desire for good, even the very thought of the good that is desired will be taken from you.