From Dom Guéranger's The Liturgical Year.
When we reflect upon the terrible events which happened in the first age of the world, we are lost in astonishment at the wickedness of man, and at the effrontery wherewith he sins against his God. How was it that the dread words of God, which were spoken against our first parents in Eden, could be so soon forgotten? How could the children of Adam see their father suffering and doing such endless penance, without humbling themselves and imitating this model of repentance? How was it that the promise of a Mediator, who was to reopen the gate of heaven for them, could be believed, and yet not awaken in their souls the desire of making themselves worthy to be His ancestors, and partakers of that grand regeneration, which He was to bring to mankind? And yet, the years which followed the death of Adam were years of crime and scandal; nay, he himself lived to see one of his own children become the murderer of a brother. But why be thus surprised at the wickedness of these our first brethren? The earth is now six thousand years old in the continued reception of divine blessings and chastisements; and are men less dull of heart, less ungrateful, less rebellious towards their Maker? For the generality of men—we mean, of those who deign to believe in the fall and chastisement of our first parents, and in the destruction of the world by the deluge—what are these great truths? Mere historical facts, which have never once inspired them with a fear of God’s justice. More favoured than these early generations of the human race, they know that the Messias has been sent, that God has come down upon the earth, that He has been made Man, that He has broken Satan’s rule, that the way to heaven has been made easy by the graces embodied by the Redeemer in the Sacraments: and yet, sin reigns and triumphs in the midst of Christianity. Undoubtedly, the just are more numerous than they were in the days of Noah; but then, what riches of grace has our Redeemer poured out on our degenerate race by the ministry of His bride the Church! Yes, there are faithful Christians to be found upon the earth, and the number of the elect is every day being added to; but the multitude are living at enmity with God, and their actions are in contradiction to their faith.
When, therefore, the holy Church reminds us of those times, wherein all flesh had corrupted its way, she is urging us to think about our own conversion. Her motive in relating to us the history of the sins committed at the beginning of the world, is to induce us to examine our own consciences. Why, too, does she read to us those pages of sacred Writ, which so vividly describe the flood-gates of heaven opening and deluging the guilty earth, if not that she would warn us against mocking that great God, who thus chastised the sins of His rebellious creatures? Last week we were called upon to consider the sad consequences of Adam’s sin, a sin which we ourselves did not commit, but the effects of which lie so heavy upon us. This week we must reflect upon the sins we ourselves have committed. Though God has loaded us with favours, guided us by His light, redeemed us with His Blood, and strengthened us against all our enemies by His grace, yet have we corrupted our way, and caused our God to repent of having created us. Let us confess our wickedness, and humbly acknowledge that we owe it to the mercies of the Lord, that we have not been consumed.[1]
The Ambrosian missal contains the following exhortation for this season of the year.
Transitorium
(Dominica in Septuagesima.)
Convertimini omnes simul ad Denm mundo corde et animo, in oratione, jejuniis, et vigiliis multis. Fundite preces vestras cum lacrymis; ut deleatis chirographa peccatorum vestrorum, priusquam vobis repentinus superveniat interitus; antequam vos profundum mortis absorbeat; et cum Creator noster advenerit, paratos nos inveniat.
Be converted to God, all ye people, in purity of heart and soul, in prayer, fasting, and much watching. Pour out your prayers with tears; that the hand-writing of your sins may be blotted out, before sudden destruction come upon you, and before the deep flood of death engulf you. When our Creator comes, let him find us ready.
[1] Lam. iii. 22.