in the Old Testament is brought out clearly by Isaiah (6:1–4) and Ezekiel (3:12). Most significant in the fact, outlined in Exodus 25, that the pattern for the earthly worship of Israel was derived from heaven. The allusion is perpetuated in the writings of the early Fathers, such as Clement of Rome, Justin Martyr, Ignatius of Antioch, Athenagoras of Athens, John Chrysostom and Pseudo-Dionysius the Areopagite. It receives acknowledgement later in the liturgical treatises of Nicolas Kavasilas and Symeon of Thessaloniki. The second, less permanent, concept was that of koinonia or "communion". This was less permanent because, after the fourth century, when it was analyzed and integrated into a theological system, the bond and "oneness" that united the clergy and the faithful in liturgical worship was less potent. It is, however, one of the key ideas for understanding a number of realities for which we now have different names. With regard to musical performance, this concept of koinonia may be applied to the primitive use of the word choros. It referred, not to a separate group within the congregation entrusted with musical responsibilities, but to the congregation as a whole. St. Ignatius wrote to the Church in Ephesus in the following way: You must every man of you join in a choir so that being harmonious and in concord and taking the keynote of God in unison, you may sing with one voice through Jesus Christ to the Father, so that He may hear you and through your good deeds recognize that you are parts of His Son. A marked feature of liturgical ceremony was the active part taken by the people in its performance, particularly in the recitation or chanting of hymns, responses and psalms. The terms choros, koinonia and ekklesia were used synonymously in the early Byzantine Church. In Psalms 149 and 150, the Septuagint translated the Hebrew word machol (dance) by the Greek word choros . As a result, the early Church borrowed this word from classical antiquity as a designation for the congregation, at worship and in song in heaven and on earth both. Concerning the practice of psalm recitation, the recitation by a congregation of educated chanters is already testified by the soloistic recitation of abridged psalms by the end of the 4th century. Later it was called prokeimenon. Hence, there was an early practice of simple psalmody, which was used for the recitation of