C.S. 路易斯在他的书 The Four Loves（《四种爱》）中谈到了保护自己免受伤害的代价。这段话的原文如下：
“To love at all is to be vulnerable. 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.”
翻译成中文：
“去爱，就意味着脆弱。爱任何事物，你的心都会被揉搓，甚至可能破碎。如果你想确保它完好无损，就不要把它交给任何人，甚至连动物都不要。用爱好和小小的奢侈品小心地包裹它，避免一切纠葛。把它安全地锁在自私的棺材或匣子里。但在那个棺材里——安全的、黑暗的、静止的、没有空气的——它会改变。它不会破碎；它会变得无法破碎、无法穿透、无法挽回。去爱，就是选择脆弱。”
