To put it mildly, I've made something of a study of the subject in my own life. I was lucky enough to spend most of my childhood with the best friends imaginable, but the luck was double-edged, because those friends were dogs, and it took me a long time to realize that the reason I wasn't finding friendships among humans that were anywhere near as strong as those I found everywhere with dogs was tragically simple: dogs are better at friendship than humans are, in just the same way that, say, humans are better at language than dogs are. "I want to know as I am known," scripture cries out, and of course that's been the driving personal dynamic of humans since they first achieved their current level of murderous sentience. The enormous conceptualizing capacity of the human brain comes with a huge price: the isolation of being the smartest, creepiest, most deceitful species on the planet, or in the planet's history.
Which makes mankind's search for simple friendship all the more moving, I guess - it certainly makes that search an all the more natural candidate for artistic treatment, and for the well-placed quip. Enright & Rawlinson's great book (yet another in a long line of great Oxford Books) is broken into many different aspects of friendship - "Among Men," "Among Women," "Youth and Age," "Animals," etc. - and each section is full of quotes and excerpts from a very pleasingly wide variety of authors. Here's a sampling:
It should be a part of our private ritual to devote a quarter of an hour every day to the enumeration of the good qualities of our friends. When we are not active, we fall back idly upon defects, even of those whom we most love. (some jasper named Mark Rutherford)
Oscar Wilde said of me 'An excellent man: he has no enemies; and none of his friends like him.' And that's quite true: they don't like me; but they are my friends, and some of them love me. If you value a man's regard, strive with him. As to liking, you like your newspaper - and despise it. I had rather you remembered one thing I said for three days than liked me (only) for 300,000,000,000,000,000 years. (George Bernard Shaw, to Ellen Terry)
A man who has few friends, or one who has a dozen (if there be any one so wealthy on this earth), cannot forget on how precarious a base his happiness reposes; and how by a stroke or two of fate - a death, a few light words, a piece of stamped paper, a woman's bright eyes - he may be left, in a month, destitute of all. (Robert Louis Stevenson, in Virginibus Puerisque)
George wondered if this was what being old meant: everything you wanted to say required a context. If you gave the full context, people thought you a rambling old fool. If you didn't give the context, people thought you a laconic old fool. The very old needed interpreters just as the very young did. When the old lost their companions, their friends, they also lost their interpreters: they lost love, but they also lost the full power of speech. (Julian Barnes, writing out his ass as usual)
Love is like the wild rose-briar,
Friendship is like the holly-tree -
The holly is dark when the rose-briar blooms
But which will bloom most constantly?
The wild rose-briar is sweet in spring,
Its summer blossoms scent the air;
Yet wait till winter comes again
And who will call the wild-briar fair?
Then scorn the silly rose-wreath now
And deck thee with the holly's sheen,
That when December blights thy brow
He still may leave thy garland green.
(Emily Bronte's "Love and Friendship," from 1839)
And we could hardly close on the subject of friendship without this last poem, even though Enright and Rawlinson choose not to include it in their anthology:
When some proud son of man returns to earth,
Unknown to glory, but upheld by birth,
The sculptor's art exhausts the pomp of woe
And storied urns record who rest below:
When all is done, upon the tomb is seen,
Not what he was, but what he should have been:
But the poor dog, in life the firmest friend,
The first to welcome, foremost to defend,
Whose honest heart is still his master's own,
Who labours, fights, lives, breathes for him alone,
Unhonour'd falls, unnoticed all his worth--
Denied in heaven the soul he held on earth:
While Man, vain insect! hopes to be forgiven,
And claims himself a sole exclusive Heaven.
Oh Man! thou feeble tenant of an hour,
Debased by slavery, or corrupt by power,
Who knows thee well must quit thee with disgust,
Degraded mass of animated dust!
Thy love is lust, thy friendship all a cheat,
Thy smiles hypocrisy, thy words deceit!
By nature vile, ennobled but by name,
Each kindred brute might bid thee blush for shame.
Ye! who perchance behold this simple urn,
Pass on--it honours none you wish to mourn:
To mark a Friend's remains these stones arise;
I never knew but one,--and here he lies.
That's of course Lord Byron, writing an epitaph for a beloved dog. He's being hyperbolic (I mentioned it was Byron, yes?), but not much more so than, say, Kipling or Burns would be. And it's hard to think systematically about the phenomenon of friendship without thinking of dogs - at least for me. The rest of you need not worry, though: you'll find this wonderful anthology for the most part very comfortingly human-oriented.