The first week of Great Lent has been known since times of old as the “dawn of abstinence,” or “clean week.” During that week, the Church persuades her children to come out of that sinful state into which all of mankind fell because our forefathers did not abstain, because they lost the blessings of heaven, the state of sin which each of us increases by his personal sins. It coaxes them into coming forth by way of faith, prayer, humility and fasting, things, which are pleasing to God. This is the time for repentance, says the Church “Behold the day of salvation, the entrance to the Fast. O my soul, be watchful, close all the doors through which the passions enter, and look up towards the Lord.” (From the first canticle of the Triodion canon at Matins on Monday of the first week of Great Lent).
The Old Testament Church, which held especially sacred the first and last days of several great feasts. Likewise, Orthodox Christians, prepared and inspired by the maternal instructions offered by their Church from antiquity, observe the first and last weeks of Great Lent especially strictly and assiduously.
The services of the first week are especially lengthy, and the podvig of physical abstinence during that week is considerably more rigorous than in the subsequent days of Great Lent. Over the course of the first four days of Great Lent, Great Compline is served, with the reading of the Great Penitential Canon of St. Andrew of Crete, which as it were sets the tone which is to resound throughout Great Lent. During the first week of Great Lent, the Canon is divided into four separate parts, one chanted at each Compline. On Thursday (actually Wednesday evening) of the fifth week of Great Lent, our attention is again directed to St. Andrew’s marvelous composition, this time in its entirety, so that with the conclusion of Great Lent in sight, we might not become lackadaisical, careless, and negligent, so that we might not forget ourselves and stop strictly watching over ourselves in everything.
The refrain “Have mercy upon me O Lord, have mercy upon me” accompanies each verse of the Great Canon. Several troparia in honor of St. Andrew, composer of the canon, and to St. Mary of Egypt are also included. The Church of Jerusalem implemented this practice during St. Andrew’s lifetime. When in the year 680 AD, St. Andrew traveled to Constantinople for the 6th Ecumenical Council, he brought with him and made public both his great composition and the life of St. Mary of Egypt, written by his compatriot and teacher, Sophronios, Patriarch of Jerusalem. The Life of St. Mary of Egypt is read together with the Great Canon at Matins on Wednesday of the fifth week of Great Lent.
The Great Canon is more astonishing than any other liturgical text encountered during Great Lent. It is a marvel of liturgical hymnography, with texts of amazing power and poetic beauty. The Church decided to call it the Great Canon not so much for its length (250 troparia, or verses), as for the quality and power of its content. St. Andrew, Archbishop of Crete, who composed the Canon in the 7th Century, also composed many other canons used by the Church over the course of the liturgical year.