So let them fall down-there's freedom waiting in the sound. When you let your walls fall to the ground.

Love anything and your heart will be wrung and possibly broken.
If you want to make sure of keeping it intact you must give it
to no one, not even 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. To love is to be vulnerable
-C.S. Lewis

C.S. Lewis was a very intelligent man, and here he is talking to those afraid to love, afraid to get hurt-afraid to risk for love. I don't think he was solely referring to the love between two people, I think he was also referring to Love between God and Yourself.
You see, there is something downright frightening about love. The thought that someone will come in and break through the walls that you have been putting up and see everything that's inside-the dirt, the sin, the bad-and the risk that as that person does that they could turn around at any minute and say, "No. That's not for me," that thought shakes the foundation of your very being. And even if that person decides to stay and accept all you've got-what if you can't deal with it anymore? What if later on they realize that it really wasn't for them? All these what ifs creep into you're thoughts and your left just saying no. No to love.And this is exactly what C.S. Lewis is saying-he's voicing those fears he's telling you that in order for you not to fear and not be vulnerable just seal your heart up. Just close it off to everything. That it will be safe, and in that dark place it will become hardened, irredeemable. Irredeemable. And so he ends, simply: To love is to be vulnerable.
In first John 4:18-it speaks of that fear. That fear of love that we have. It says:

There is no fear in love, but perfect love drives out fear.

This is where I think C.S. Lewis was referring to God. There is nothing to fear. Because God's love-it's unconditional. It's everlasting. It is not depending on what you have behind those walls-because He has already seen past those walls. He saw where you were wounded, He saw where you fear you will be hurt. He saw you build those walls up, and He wept. He wept for you-and Your broken heart. His love is like the wind-you can't see it but you can feel it. It wraps around You. Wraps around those walls-and is slowly whispering to you to bring them down. To go brick by brick and tear the wall down. He is the God who sees You. His Love is everlasting. When you open your heart to His love-His love that won't hurt you, that will only heal you. That perfect love. It's perfect. Nothing on earth compares with His love. No love. No one. His perfect love covers you-and it drives out your fear.
So there's two choices. Wrap your heart, keep it, hide it-and let it become irredeemable. Or come to the greatest Lover of all. And let HIS perfect love drive out your fear. Open your heart to love. To the REAL LOVE.