Lovers are normally face to face, absorbed in each other; Friends, side by side, absorbed in a common interest...true Friendship is the least jealous of loves. Two friends delight to be joined by a third, and three by a fourth...Friendship exhibits a glorious "nearness by resemblance" to Heaven itself where the very multitude of the blessed (which no man can number) increases the fruition which each has of God...Friendship arises out of mere Companionship when two or more of the companions discover that they have in common some insight or interest or even taste which the others do not share and which, till that moment, each believed to be his own unique treasure (or burden)...The very condition of having Friends is that we should want something else besides Friends...Friendship must be about something, even if it were only an enthusiasm for dominoes or white mice. Those who have nothing can share nothing; those who are going nowhere can have no fellow-travelers...If, at the outset, we had attended more to him and less to the thing our Friendship is "about", we should not have come to know or love him so well. You will not find the warrior, the poet, the philosopher or the Christian by staring in his eyes as if he were your mistress: better fight beside him, read with him, argue with him, pray with him."
C.S.Lewis
The Four Loves pp.91-104