3 And he spoke to them this parable, saying: 4 What man of you that hath an hundred sheep: and if he shall lose one of them, doth he not leave the ninety-nine in the desert, and go after that which was lost, until he find it?
Gregory: He gave a comparison which man might recognize in himself; though it referred to the Creator of men. For since a hundred is a perfect number, He Himself had a hundred sheep.
Cyril: We may hence understand the extent of our Savior’s kingdom. For He says there are a hundred sheep, bringing to a perfect sum the number of rational creatures subject to Him. For the number hundred is perfect, being composed of ten decades. But out of these one has wandered, namely, the race of man which inhabits earth.
Ambrose: Rich then is that Shepherd of whom we all are a hundredth part.
Gregory: He left the companies of the Angels in heaven. But man then forsook heaven when he sinned. And that the whole body of the sheep might be perfectly made up again in heaven, the lost man was sought for on earth.
Cyril: Was He then angry with the rest, and moved by kindness only to one? By no means. For they are in safety, the right hand of the Most Mighty being their defense. It behoved Him rather to pity the perishing, that the remaining number might not seem imperfect. For the one being brought back, the hundred regains its own proper form.
Augustine: Or He spoke of those ninety and nine whom He left in the wilderness, signifying the proud, who bear solitude as it were in their mind, in that they wish to appear themselves alone, to whom unity is wanting for perfection. For when a man is torn from unity, it is by pride; since desiring to be his own master, he follows not that One which is God, but to that One God ordains all who are reconciled by repentance, which is obtained by humility.
Scripture from the Douay-Rheims Bible. Commentary from St. Thomas Aquinas, Catena Aurea, Vol. III (London: Rivington, 1843).