Matthew 18: 12 - 14
12 What do you think? If a man has a hundred sheep, and one of them has gone astray, does he not leave the ninety-nine on the mountains and go in search of the one that went astray?
13 And if he finds it, truly, I say to you, he rejoices over it more than over the ninety-nine that never went astray.
14 So it is not the will of my Father who is in heaven that one of these little ones should perish.

EWTN