There is one method which, if practiced with full attention, will seldom allow anything passionate to slip unnoticed into the heart. This is to examine our thoughts and feelings, so as to discover which they tend: towards pleasing God or towards pleasing ourselves.
As a general rule, decide whether a thing is permissible by the effect it produces within. Permit yourself what is constructive, but never what is destructive.
Many people will be found pleasing God, for whom it will be possible, in the mountains and in desert places, to save themselves by much prayer….for God, seeing their many tears and sincere faith, will have mercy on them, as a tender Father, and will keep them.
The zealous are eager for ascetical struggles of self-forcing and self-opposition with the aim of self-correction, or of raising themselves to primordial purity, so that they might all the more speedily become worthy of communion with God. Obviously the more eager one is, the more diligently and longingly he does this, the sooner he achieves his goal.
The brothers said, 'Why is it that the monks are obliged to go around begging for the food and clothes they need, like those who are in the world, although our Lord promised them, saying, ‘Seek ye first the kingdom of God and its righteousness, and that of which ye have need shall be given to you’ (Matt. 6:23)?' The old man said, 'This saying is a proof of the wisdom and grace of God toward those who are in the world, for in the majority of cases, the righteousness of the children of this world consists of alms and compassion; but the children of light are righteous people and monks who, in their persons, and in their bodies, and in their thoughts, serve our Lord. And God has made the monks to have need of the children of this world because of His love, so that they may care for each other, and may pray for each other; that is to say, the children of the world must care for the monks and the monks must pray in love for them. And as the children of the world make the monks associates with them in the corporeal things of the world, the monks must make the children of the world to be associates with them in the things of heaven, for our Lord spoke to the children of the world, saying, ‘Make ye to yourselves friends of this mammon of iniquity so that when they have become perfect they may receive you into their tabernacles which are forever.’ (Luke 14:9)
I am a Christian, you say, and content yourself with this. This is the first deceit - transferring to yourself the privileges and promise of Christianity, without any care to root true Christianity into yourself; or to ascribe to yourself that which can only be acquired by your strength and inner worthiness. Explain to yourself that it is illusory to hope in a name, that God can raise a son of Abraham from a stone and can take away your promise at any time if the conditions for participating in them are not soon fulfilled. Mainly, clarify to yourself what it means to be a Christian, unite yourself to this ideal, and you will see just how stable is this buttress to your blindness.
At this point the zealous man looks inward, and what do you think he finds there? Ceaseless wandering of thoughts, constant onslaughts from the passions, hardness and coldness of heart, obstinacy and disobedience, desire to do everything according to his own will. In a word, he finds everything within himself in a very bad state. And seeing this, his zeal is inflamed, and he now directs strenuous efforts to the development of his inner life, to controlling his thoughts and the dispositions of his heart. From directions on inner spiritual life he discovers the necessity of paying attention to oneself, of watching over the movements of the heart. In order not to admit to anything bad, it is necessary to preserve the remembrance of God. And so he sets to work to achieve this remembrance. But his thoughts can no more be arrested than the wind; his bad feelings and worthless impulses can no more be evaded than the stench of a corpse; his mind, like a wet and frozen bird, cannot rise to the remembrance of God. What is to be done? Be patient, they say, and go on working. Patience and labor are exercised, but all within remains the same. At last someone of experience is found who explains that all is inwardly in disorder because the forces within are divided: mind and heart each go their own way. Mind and heart must be united; then wandering of thoughts will cease, and you will gain a rudder to steer the ship of your soul, a lever by which to set in movement all your inner world. But how can one unite mind and heart? Acquire the habit of praying these words with the mind in the heart, 'Lord Jesus Christ, Son of God, have mercy upon me'. And this prayer, when you learn to perform it properly, or rather when it becomes grafted to the heart, will lead you to the end which you desire. It will unite your mind with your heart, it will cut off your wandering thoughts, and give you the power to govern the movements of your soul.
Woe is he who knowingly chooses to sin with the intention to repent when morning comes, for he knows not what the coming day or the night that precedes it will bring.
The root of good inner order is the fear of God. Preserve this fear within you constantly: it will hold everything taut, and will allow no slackness either in physical members or thoughts, creating a vigilant heart and a sober mind, and allowing no bodily torpor or blurring of thought. But one must always remember that success in any aspect of the spiritual life is the fruit of the grace of God. Spiritual life comes entirely from His most Holy Spirit. We have our own spirit but it is void of power. It begins to gain strength only when the grace of God flows in it.