This repetition of truth shows us that Jesus is telling us something important. Second, we are told that no one can remove us from the Savior's flock. There are two things a Shepherd must do in defense of the sheep. He must protect the sheep from outside predators. He must protect the sheep from themselves.
Sheep are naturally prone to wander, to get in trouble, to do foolish things.
Jesus knows that . . . . He protects the sheep from themselves. This is a doctrine many reject. It is a doctrine that many can abuse. However, that doesn't change what Jesus is saying.