Fr Zacharias Zacharou in his book The Hidden Man of the Heart, explains the gift of speaking in tongues and why it was given to the Church on the day of Pentecost. "We know that the gift of speaking in tongues (glossolalia) was given to the nascent Church for a specific purpose.
The old Israel had become accustomed to worshiping and praying in a largely external manner, and when the Spirit came on the day of Pentecost, He wanted this to change. His intention, therefore was to teach the people to pray in spirit, in the 'hidden man of the heart' (I Peter 3:4). p.176
Those who prayed in tongues were happy being certain of one thing: God had broken into them and was at work in them. St Paul distinguishes between prayer in the spirit (pneuma) and prayer in the mind (nous* - see note) and identifies prayer in the spirit with praying in foreign tongues. (1 Cor. 14:15 and 1 Cor 14:14).
"For St Paul, spirit and mind are almost identical: he sometimes says that the highest purpose of Christianity is the renewal of the spirit and sometimes the renewal of the nous* (mind). Nevertheless in trying to distinguish between the two, I would say that the spirit is present in the mind as something higher, deeper than the mind itself - that is revealed through the mind, just as the soul can be said to be revealed through the emotions". p.177
Prayer in the spirit is identified with prayer in tongues, when man's spirit is aware of the irruption of God into his life. In this kind of prayer the highest faculty of the human being is inspired by God, receiving his energy. Man then surrenders to the breath of the Holy Spirit, .., and the Spirit intercedes with unutterable groanings (Rom. 8:26) for those in whom He dwells, sometimes with words which are beyond the understanding of the psychological man.
In prayer of the mind, by contrast, the mind rises toward God in pious thought and godly desire. Such prayer is characterized by holy contrition or joy, but it is not liable to surrender to the great impetus and boundless spiritual exaltation we have just described. A degree of control is exercised by the person who prays in the mind (nous*): he is able to direct his thoughts, desires and feelings.
Total surrender to glossolalia (speaking in tongues) involves a certain loss of control: it is an explosion of grace and joy, and while we are fully aware that God is within us, somehow we deny ourselves any awareness of our fellow members of the Body.
The best explanation for God's gift of tongues to the early Church lies in the necessity of teaching newly converted Christians to pray with their heart rather than just externally, as they were likely to have been used to doing, But the Church soon discovered a deeper way to educate the heart, for She was concerned to cultivate the inner man. She discovered the invocation of the Name of our Lord Jesus Christ. And little by little, the Prayer of the Heart replaced the gift of speaking in tongues. The Jesus Prayer is a way of praying in the spirit without loosing any control of the spirit, and therefore, without running the risk of usurping the space of the other members of the Body of Christ.
If this gift (speaking in tongues) has indeed been given temporarily to some people, perhaps it will enable them to discover the true unbroken Tradition of the Church, the Tradition of the Prayer of the Heart, which is the surest and humblest prayer in the edification, inspiration and salvation of man.. Through this prayer we receive the greatest of all the gifts of the Holy Spirit, the gift which will heal our nature and strengthen it 'guiding us into all truth' (John 16:3). It will enable us to bear the fullness of divine love. And this gift will never outlive its purpose - indeed it will accompany us beyond the grave.
It is important that we understand this phenomenon of glossolalia- we must not be seduced by it. But let us above all be gracious to those who believe they have experienced this gift and gently point out to them that it is the beginning of something far greater that will lead them to the heart of the Tradition.
Selections from 'The Hidden Man of the Heart' by Archimandrite Zacharias Zacharou, Mount Thabor Publishing 2008 p. 176 to p.189.
*The word 'mind' (nous) as used by Fr Zacharias in this text, does not refer to reason, discursive thinking or logical thinking, but to the organ of the soul by which the soul can 'know', that is directly apprehend, spiritual realities; not by drawing conclusions, but directly under the inspiration of divine Grace. The Greek language makes a distinction between nous (translated as 'mind' here) which is the spiritual organ of knowledge of the soul; and diania or 'reason' the organ of knowledge of the brain through the senses and discourse (logical thinking). Orthodox Christian anthropology affirms that man has both organs of knowledge. Thoughts, reason and the senses can interact with the nous, both in a positive and in a negative manner, and in that way affect the heart, the spiritual center of man.
This book is available from Mount Thabor Publishing