One of the first things I learned about sheep is that when they have lambs there is a unique grunt the mother ewe makes to call her child. It is not the bleating we are used to thinking of when a sheep speaks, but rather a low grunt almost. What is interesting is that they start this immediately upon the birth of the lamb while they are cleaning it off. To the untrained ear, each grunt sounds the same, however, everyone is unique.
I wondered why until I realized the purpose of this grunt. It was to help the lamb identify the mother's call from all the rest. Sheep tend to lamb "in season" meaning all close together. So this call is extremely important for when the mother wants to have the lamb near. It was personal, unique, and intimate.
The Good Shepherd is much the same with his sheep. Each one He calls to himself in His own unique way and that call he uses sets the tone for that relationship for the rest of that child's life. Some are drawn through preaching, others are moved by music, some through the kindness of a stranger, others are knocked off their horse on their way to persecute the body of Christ.
What I love so much about this is the deeply personal way it means the Shepherd knows his sheep. Each are different and unique in their own way, yet He knows them all by name and He has a very unique relationship with each one!