Love anything, and your heart will certainly be wrung and possibly broken.  If you want to make sure of keeping it intact, you must give your heart to no one, not even to an animal.  Wrap it carefully round with hobbies and little luxuries; avoid all entanglements; lock it up safe in the casket or coffin of your selfishness.  But in that casket—safe, dark, motionless, airless-it will change.  It will not be broken; it will become unbreakable, impenetrable, irredeemable.  The alternative to tragedy, or at least to the risk of tragedy, is damnation.
-C. S. Lewis

“Most assuredly, I say to you, he who does not enter the sheepfold by the door, but climbs up some other way, the same is a thief and a robber. But he who enters by the door is the shepherd of the sheep. To him the doorkeeper opens, and the sheep hear his voice; and he calls his own sheep by name and leads them out. And when he brings out his own sheep, he goes before them; and the sheep follow him, for they know his voice. Yet they will by no means follow a stranger, but will flee from him, for they do not know the voice of strangers.” Jesus used this illustration, but they did not understand the things which He spoke to them. (John 3:3-6)

John Piper has been busy!