More research on friendship. And now I'm turning to CS Lewis' The Four Loves. (I was mesmerised by his chapters on friendship and affection, but embarrassed to say I understood only 40 per cent of his writing on romantic love.)

I was taken by this section on love, safety and self-protection.

Lewis tells of St Augustine, who lost his best friend and wrote about how devastated he was.

“This is what comes of giving ones heart to anything but God," said Augustine. "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.”

It would be nice to always agree with the ancient Christian greats, but Lewis takes issue with his sentiments.

Instead he argues that Augustine's position is the safe option.

Lewis writes: “Of all the arguments against love, none makes so strong an appeal to my nature as ‘careful, this might lead you to suffering!’ "

"But when I respond to that appeal I seem to be a thousand miles from Christ. If I am sure of anything, I am sure that his teaching was never meant to confirm my preference for safety.... God himself doesn’t have insurance against heartbreak."

"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 an animal. Wrap it carefully around 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, but it will become unbreakable, impenetrable, irredeemable. The alternative to tragedy (or the risk or tragedy) is damnation. The only place outside heaven where you can be perfectly safe from all the dangers nad perturbations of love is Hell."