Two, far from being the necessary number for Friendship, is not even the best. And the reason for this is important. Lamb says somewhere that if, of three friends (A,B, and C), A should die, the B loses not only A but A’s part in B. In each of my friends there is something that only some other friend can fully bring out. By myself I am not large enough to call the whole man into activity; I want other lights than my own to show all his facets. Now that Charles is dead, I shall never again see Ronald’s reaction to a specifically Caroline joke. Far from having more of Ronald, having him ‘to myself’ now that Charles is away, I have less of Ronald. Hence true Friendship is the least jealous of loves.
—C. S. Lewis