The enemy of our salvation especially strives to draw our heart and mind away from God when we are about to serve Him, and endeavors to adulterously attach our heart to something irrelevant. Be always, every moment, with God, especially when you pray to Him. If you are inconstant, you will fall away from life, and will cast yourself into sorrow and straitness.
According to the teaching of the Fathers, any impression which, touching the heart, fills it with a great irritation, must come from the region of passions. Therefore impulses which spring from the heart should not be followed at once, but only after careful examination and fervent prayer. God preserve us from a blind heart! It is well known that passions do blind the heart and screen the shining sun of the mind that we should all strive to gaze at.
We ought not to grieve or become irritated at anything because, by frequent vexation and irritability, we form the morally and physically very injurious habit of irritability, whilst by bearing opposition with equanimity we form the good and useful habit of enduring everything calmly and patiently.
You ask for some way of completely eradicating irritability. The inclination to irritability is given us to use against sin, and we were never meant to use it against our fellow men. When we do, we act contrary to our true nature.
Monasticism itself is a perpetual labor of conquering passions and uprooting them in order that, being in a pure and immaculate state, one may preserve oneself before the face of God. This, then, is your task! Give your attention to it, and direct all your powers towards it.
Let no one on seeing or hearing something supernatural in the monastic way of life fall into unbelief out of ignorance; for where the supernatural God dwells, much that is supernatural happens.
In the heart is the will; in the heart is love; in the heart is the mind--in the heart is the image of the divine Trinity. The heart is the home of the Father, the altar of the Son and the workshop of the Holy Spirit. God wants our hearts: Son, give Me thy heart. Oh, my brother, above and beyond all else that you keep safe, guard your heart. Let the mountains be overthrown and the seas dried up; let friends forsake you and riches betray you; let your body be eaten by worms; let the world pour on you all the scorn of which it is capable--and do not fear. Only guard your heart; guard it and make it cleave to the Lord; give it into His keeping. Life flows from the heart; but whence comes this life in the heart, unless it is the abode of the breath of the Lord and Source of life-God? Oh, my brother, the Spirit of God Himself can, when He so desires, dwell in the human heart. He not only can, but wills to do so. Only, He waits for you to prepare your heart for Him; to make it into a temple, for God the Holy Spirit only lives in a temple. As a snake protects its head, so, my son, guard your heart. For the life that comes from the living God enters into it and flows forth from it.
Those who fervently desire to remain amid (in the world) as well as those who live a worthy life in communities, in mountains and in caves are saved; and God bestows on them great blessings solely because they rest their faith in Him.
Truly wretched and three times miserable is the soul that has left the world and dedicated itself to God but has not lived in a manner worthy of its promise. Then, brothers, let us not allow this age, which is short and contemptible and passes like a shadow, to steal that blessed and immortal life away from us.
And the old man also said, 'God saith unto thee thus -- if thou lovest Me, O monk, do that which I ask, and do not that which I do not desire. For monks should lead lives wherein they act not in iniquity, and a man should not look upon evil things with his eyes, no hear with his ears things which are alien to the fear of God, nor utter calumnies with his mouth, nor plunder with his hands; but he should give especially to the poor, and he should not be unduly exalted in his mind, and he should not think evil thoughts, neither should he fill his belly. Let him do then all these things with discretion, for by them is a monk known.' The old man also said, 'These things form the life of a monk: good works, and obedience, and training. A man should not lay blame on his neighbor, and he should not utter calumnies, and he should not complain, for it is written, 'The lovers of the Lord hate wickedness.'
A monk is he who wants to sleep and does not sleep, who wants to eat and does not eat, who wants to drink and does not drink. A monk is distinguished by ‘continual forcing of nature.’
Monastic life is called the art of arts and the science of sciences; for it does not bring perishable blessings akin to the things of this world, which drive the mind from what is best and engulf it; but monk hood promises us wonderful and unspeakable treasures which the ' Eye that not seen, nor ear heard, neither have entered into the heart of man' (1 Cor. ii. 9). Hence, ' we wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world' (Ephes. vi. 12). If therefore present existence is but darkness, let us flee from it, let us flee by returning our mind and our heart. Let us have nothing in common with the enemy of God, for 'whosoever will be a friend of the world is the enemy of God' ( James iv. 4). And who can help the enemy of God ? Therefore let us imitate our fathers and, like them, let us seek the treasure existing within our hearts and, having found it, let us hold fast to it in doing and guarding - for which task we were destined from the beginning.