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 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.
Archpriest Victor Potapov tells us more about it in this article >> https://orthochristian.com/128944.html
These services were recorded at St. George Greek Orthodox Church, Des Moines, IA