Luke 15:1–7

Verse 4. What man, and so forth Christ left the ninety-nine in the desert, when he descended from the angelic choirs, in order to seek last man on the earth, that he might fill up the number of the sheepfold of heaven, from which his sins had excluded him. Saint Ambrose—Neither did his affection for the last sheep make him behave cruelly to the rest; for he left them in safety, under the protection of his omnipotent hand. S. Cyril de D. Thoma Aquin.

Verse 7. Joy in heaven, and so forth What incitement ought it not to be to us to practise virtue, when we reflect that our conversion causes joy to the troops of blessed spirits, whose protection we should always seek, and whose presence we should always revere. Saint Ambrose—There is greater joy for the conversion of a sinner, than for the perseverance of the just; but it frequently happens, that these being free from the chain of sin, remain indeed in the path of justice, but press not on eagerly to their heavenly country; whilst such as have been sinners, are stung with grief at the remembrance of their former transgressions, and calling to mind how they have forsaken their God, endeavour by present fervour to compensate for their past misconduct. But it must be remembered that there are many just, whose lives cause such joy to the heavenly court, that all the penitential exercises of sinners cannot be preferred before them. Saint Gregory, hom. xxxiv.