In his letter to the Romans St. Paul instructs Christians to “be constant in prayer.” (Romans 12:12) In his first letter to the Thessalonians he says simply, “pray without ceasing.” (I Thessalonians 5:17)
These two commands of the apostle have been interpreted in the Orthodox tradition in two different ways. The first way, mentioned by St. John Chrysostom and St. Dimitry of Rostov, is that Christians should have regular times for prayer which they never skip - “in the evening and the morning and at noon day” (Psalm 55:17) - and then in between they should always remember God and do all things to His glory (cf. I Corinthians 10:31), offering up supplications and petitions as the need may arise, praising and thanking when the occasion requires it. Such is the normal way that all Christians must live.
Prepare for your set times of prayer by unceasing prayer in your soul, and you will soon make progress. (St. John of the Ladder, Step 28)
The set times of prayer are very important, and should not be put aside for any reason, even when one prays continuously in his heart. This is the teaching and practice of the saints. Each person desiring to live the spiritual life should have his own rule of prayer. It should be brief and regular, such that it could be kept in all conditions and circumstances. In this set rule of prayer, the prayers of the Church should be used, the Lord’s Prayer and those from the prayer book. This gives discipline in prayer and provides instruction and inspiration in prayer which is perfectly trustworthy and sound, having demonstrated its power in the lives of the saints. A person who does not follow a set rule of prayer using the traditional prayers of the Church runs the great risk of impoverishing his prayer and reducing its dimensions and scope to the limited perspective of his own individual desires and needs.
When praying with a set rule of prayer, the spiritual teachers tell us to put our whole mind and heart into the meaning of the words, not merely “saying prayers,” which is not prayer at all, but genuinely praying through personal attention and fervor. They tell us to allow our mind not to wander from the words of the prayer, but to use the given words as the basis of our own personal devotion, even allowing our mind to go beyond the given words to our own words, or to no words in the prayer of silence, if the Lord leads us this way. They also tell beginners - and St. Dimitry of Rostov says that we are all beginners, no matter how advanced - never to go back and repeat prayers done poorly. They tell us rather to put ourselves at the mercy of God, and to try to do better the next time. This method reduces the possibility of thinking that God hears our prayers according to the perfection of our performance and not according to the greatness of His mercy, and safeguards against both pride and despair. It gives humility and hope, and keeps us always forging ahead. (cf. Luke 9:62, Philippians 3:13-15)
Thus when one finishes his rule of prayer, however well or poorly he has done it, he should say Amen, and go about his business of living in Christ, remembering God and doing His will until the next time comes for the rule of prayer to be done. Then he should do it as well as he can, beginning all over again.
The second way of interpreting the teachings about unceasing prayer is that men should actually pray with conscious awareness at every moment of their lives, and even in their unconscious selves while their bodies are sleeping. This understanding of “unceasing prayer” was developed in the monastic tradition, but then spread rapidly throughout the whole membership of the church. It became very popular in recent times, mostly through the appearance of the book by the anonymous Russian peasant called The Way of the Pilgrim.
The search for active “unceasing prayer” has its source not only in the instruction of Saint Paul, but also in the literal interpretation of such words of the psalmist:
I will bless the Lord at all times; his praise shall continuously be in my mouth. (Psalm 34:1)
And of the Song of Solomon:
I slept, but my heart was awake. (Song 5:2)
The method of “unceasing prayer” is to have a brief prayer verse, usually the Jesus Prayer (see p. 131ff.) which is repeated over and over, literally hundreds of times throughout the day and night, until it becomes perpetually implanted in the heart as a “bubbling spring,” a continual presence in the soul calling out to the Lord. (cf. Theophan the Recluse, 19th c., The Art of Prayer) It is often, but not necessarily, connected with one’s breathing, so much so that it is uttered “with every breath.” (St. Gregory the Theologian; St. John Chrysostom) It begins by being said vocally, silently with the lips, and then it becomes wholly mental. The claim is made that one can continue this “unceasing prayer” even while engaged in the normal activities of life, while reading or writing, and even while sleeping, thus the “body sleeps,” but the “heart is awake.” Then, whenever one’s attention to the affairs of life cease, or when one awakes from one’s bed, one finds that the prayer is continuing itself.
The prayer is also known to break through one’s consciousness with power in times of temptation or stress, appearing, as it were, of its own accord. (cf The Art of Prayer, Igumen Chariton, ed.)
We are not commanded to work, keep vigil or fast without ceasing, but we are commanded to pray without ceasing. For…prayer purifies, and strengthens the mind which was created to pray…and to fight the demons for the protection of all the powers of the soul. (Evagrius of Pontus, 4th c.)
He who has entered his room (i.e. his heart) and prays without ceasing has included in this all prayer everywhere. (St. Mark the Ascetic, 4th c., Direction from Discourses)
Let no one think, my brother Christians, that it is the duty only of priests and monks to pray without ceasing, and not of laymen. No, no; it is the duty of all Christians to remain always in prayer.
...bear in mind the method of prayer - how it is possible to pray without ceasing, namely by praying in the mind. And this we can do always if we wish. For when we sit down to work with our hands, when we walk, when we eat, when we drink we can always pray mentally and practice this mental prayer - the true prayer pleasing to God.
Blessed are those who acquire this heavenly habit, for by it they overcome every temptation…
This practice of inner prayer tames the passions…by it the dew of the Holy Spirit is brought down into the heart…
This mental prayer is the light which illumines man’s soul and inflames his heart with the fire of love for God. It is the chain linking God with man and man with God. Oh, the incomparable blessing of mental prayer. It allows a man constantly to converse with God.
And what other and greater rewards can you wish than this, when…you are always before the face of God, constantly conversing with Him - conversing with God, without whom no person can ever be blessed, either here or in the life still to come. (St. Gregory Palamas, 14th c., How All Christians In General Must Pray Without Ceasing)