Are not all lifelong friendships born at the moment when at last you meet another human being who has some inkling (but faint and uncertain even in the best) of that something which you were born desiring, and which, beneath the flux of other desires and in all the momentary silences between the louder passions, night and day, year by year, from childhood to old age, you are looking for, watching for, listening for? You have never had it. All the things that have ever deeply possessed your soul have been but hints of it–tantalizing glimpses, promises never quite fulfilled, echoes that died away just as they caught your ear. But if it should really become manifest—if there ever came an echo that did not die away but swelled into the sound itself—you would know it. Beyond all possibility of doubt you would say ‘Here at last is the thing I was made for.’ We cannot tell each other about it. It is the secret signature of each soul, the incommunicable and unappeasable want, the thing we desired before we met our wives or made our friends or chose our work, and which we shall still desire on our deathbeds, when the mind no longer knows wife or friend or work. While we are, this is. If we lose this, we lose all.
The Problem of Pain, C. S. Lewis, Chapter: Heaven, page 150-151.