Durandus goes into considerable detail about Sundays and other periods and occasions throughout the Church year. Here however, as elsewhere in other answers, he shares only an introduction in answer to the questions asked. So what can we learn regarding the third Sunday of Lent?
The third Sunday of Lent belongs to confession, and the fourth to renewal. For, as has been said previously, the Lord, on the first Sunday of Lent, arms His soldiers and on the second, He shows them the reward. It only remains for Him to show them the way by which we reach this supreme goal, that is to say, by confession and repair. This Sunday therefore belongs to confession.
Now, there is a double confession, namely, the confession of sin and the confession of praise, and a man must possess both. By the humility of confession, man expects from God all that he must expect, that is, deliverance, the gift of grace, and all other spiritual benefits. This is why the Introit, ‘My eyes are ever towards the Lord, etc.’ (Psalm 25:15-16, 1-2) is of the seventh tone, because it is the grace of the seven gifts of the Holy Spirit that will tear a man from the nets of the devil. This is because by confession one scrutinizes the evil in all its depth, which is why one makes a station to St Lawrence, who was delivered by confession. This humility delivered Joseph from the hands of his brothers and from prison and that is why, in the Night Offices, we sing a passage about it.
This Sunday is also the sixth since the Septuagesima and it was on the sixth day of the week, Friday, that the Lord was crucified. That is why we mention the Passion of the Lord, which is signified by Joseph, who is also related to what is said today. For Christ was delivered, by humility, from the pitfalls of His brothers, that is to say the Jews, and He was raised above all Egypt, that is to say the whole world. Thus, what happened to Joseph literally means Christ in the spiritual sense, and the Night Office follows the order of their story. On the previous Sunday, the history of Jacob was sung, while on this one sings that of Joseph, who, sold by his brothers, came to their aid during the famine. Christ, too, crucified by the Jews, redeemed the human race by His death, and by redeeming them, delivered them from the devil, as it is read in the Gospel of this day.