In words which can still bring tears to the eyes, St Augustine describes the desolation in which the death of this friend Nebridius plunged him. Then he draws a moral. This is what comes, he says, of giving one’s heart to anything but God. All human beings pass away. Do not let your happiness depend on something you may lose. If love is to be a blessing, not a misery, it must be for the only Beloved who will never pass away.

   Of course this is excellent sense. Don’t put your goods in a leaky vessel. Don’t spend too much on a house you may be turned out of. And there is no man alive who responds more naturally than I to such canny maxims. I am a safety-first creature. Of all arguments against love none makes so strong an appeal to my nature as ‘Careful! This might lead you to suffering.’

   To my nature, my temperament, yes. Not to my conscience. When I respond to that appeal I seem to myself to be a thousand miles away from Christ. If I am sure of anything I am sure that His teaching was never meant to confirm my congenital preference for safe investments and limited liabilities. . . There is no escape along the lines St Augustine suggests. Nor along any other lines. There is no safe investment. To love at all is to be vulnerable. Love anything, and your heart will certainly be wrung and possibly be 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. The only place outside of Heaven where you can be perfectly safe from all dangers and perturbations of love is Hell. 

The Four Loves - C.S. Lewis