tends to be highly rigorous and very strict, especially with clergy) an unalterable validity also does not apply, since canons deal with living on earth, where conditions are always changing and each case is subject to almost infinite variation from the next. By tradition, the Eastern Orthodox Church, when faced with issues that are larger than a single bishop can resolve, holds a local council. The bishops and such others as may attend convene (as St. Paul called the Corinthians to do) to seek the mind of the church. A council's declarations or edicts then reflect its consensus (if one can be found). An ecumenical council is only called for issues of such import or difficulty or pervasiveness that smaller councils are insufficient to address them. Ecumenical councils' declarations and canons carry binding weight by virtue of their representation across the whole church, by which the mind of the church can be readily seen. However, not all issues are so difficult as to require an ecumenical council to resolve. Some doctrines or decisions, not defined in a formal statement or proclaimed officially, nevertheless are held by the church unshakably and unanimously without internal disturbance, and these, also reflecting the mind of the church, are just as firmly irrevocable as a formal declaration of an ecumenical council. Lack of formality does not imply lack of authority within holy tradition. Territorial expansion and doctrinal integrity As the church increased in size through the centuries, the logistic dynamics of operating such large entities shifted: patriarchs, metropolitans, archimandrites, abbots and abbesses, all rose up to cover certain points of administration. Liturgy Church calendar Lesser cycles also run in tandem with the annual ones. A weekly cycle of days prescribes a specific focus for each day in addition to others that may be observed: Church services Music and chanting For the composition of religious chant, the Octoechos, an eight-tone (mode) system, analogous to the Gregorian modes in the West, and to other ancient Christian musical systems, is used. Byzantine music is microtonal. Northern Slavs, however, have used simpler tonal systems evolved through the sundry local types of Znamenny chant; today Western music, often with four-part harmony, and the "tones" are simply sets of melodies. There are numerous versions and styles that are traditional and acceptable and these vary a great deal between cultures. Traditions Monasticism The Eastern Orthodox Church places emphasis and awards a high