« Companionship is [...] often called Friendship, and many people when they speak of their friends mean only their companions. But it is not Friendship in the sense I give to the word. By saying this I do not at all intend to disparage the merely Clubbable relation. We do not disparage silver by distinguishing it from gold.
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 typical expression of opening Friendship would be something like, ‘What? You too? I thought I was the only one.’ [...] It is when two such persons discover one another, when, whether with immense difficulties and semi-articulate rumblings or with what would seem to us amazing and elliptical speed, they share their vision—it is then that Friendship is born. And instantly they stand together in an immense solitude.
All who share [a common activity, a common recreation, common studies] will be our companions; but one or two or three who share something more will be our Friends. In this kind of love, as Emerson said, Do you love me? means Do you see the same truth?—Or at least, Do you care about the same truth? The man who agrees with us that some question, little regarded by others, is of great importance, can be our Friend. He need not agree with us about the answer.
Notice that Friendship thus repeats on a more individual and less socially necessary level the character of the Companionship which was its matrix. The Companionship was between people who were doing something together—hunting, studying, painting or what you will. The Friends will still be doing something together, but something more inward, less widely shared and less easily defined; still hunters, but of some immaterial quarry; still collaborating, but in some work the world does not, or not yet, take account of; still travelling companions, but on a different kind of journey. »
— C.S. Lewis, The Four Loves















