There are two famous quotations which for some reason have always stuck in my mind regarding friendship and the competing demands of loyalty. The first is by E.M. Forster, the distinguished English novelist--
"If I had to choose between betraying my country and betraying my friend, I hope I should have the guts to betray my country."
The second is by Graham Greene, another distinguished English novelist from a later generation--
"If you have to earn a living...and the price they make you pay is loyalty, be a double agent--and never let either of the two sides know your real name."
Forster was a Gay man, who grew up and lived at a time when homosexuality was still legally a crime in Great Britain. His sentiments regarding loyalty and friendship have a specific poignancy, in light of the conditions under which he was forced to live during the better part of his life. Later, he would confront loyalty in the political sphere, but his feelings were always informed by the tension between private (and even secret) loyalties and public duty.
Greene occupied for most of his life a dual role, as public servant, and novelist--a complex, worldly man, with many competing loyalties (church, state, family, art), in addition to a restless, wayward nature, and a tortured conscience. The Author both of "straight" novels, and mystery whodunits (which he famously called "entertainments"), he drew deeply upon his cosmopolitan familiarity with exotic settings: Africa, Central America, East Asia. One of the dominant themes in his work is just this very issue of personal attachment versus political, or public duty. In The Third Man, for instance, the American Western genre writer Holly Martins comes to post-War Vienna to see his old friend Harry Lime; ultimately he discovers that Lime has been trafficking in black market fake medicines, and is now underground, eluding the Authorities in the Western Sector. In the course of his inquiries, Martins falls in love with Lime's girlfriend, Anna Schmidt. The Authorities want him to rat out his friend, Anna wants to protect Lime, whom she still loves, and Martins still feels drawn to his corrupt old friend. It's vintage Greene, and sets into motion all the classic claims on loyalty (friendship, love, duty, morality)--particularly the value we place on personal friendship.
There is no neat distinction between love and friendship. Indeed, it is possible to be a friend and a lover to someone at the same time, though complications may arise. Relationships which begin in love, may develop into lasting friendships, and vice versa. More often, we tend to think of friendships as less intense than love, or as having a somewhat different character. Love may occur between individuals for whom other levels of interaction are unlikely. Friendships may be destroyed by allowing them to "descend" into the carnal.
In the modern world, friendship has often been the testing ground for character. Our allegiances to individuals are often pitted against our commitment to groups, political principles or the demands of conduct. At the level of the family or clan, we are often torn between loyalty to our immediate relations, and those of religion, country or ideology. How we mediate between these demands is a measure of strength of character, or lack of it.
The Forster quote seems to come down on the side of friendship, as being a more powerful and preferable attachment than patriotism. It's attractive, because it places allegiance to individual--possibly an individual--above duty to country, presumably even--or particularly--in time of great stress, such as under wartime conditions. If we cannot depend upon our closest friends, then upon what foundation is our individual freedom and honor to be constructed? One can think of exceptions which might break such a vow, i.e., if one's friend had committed an heinous crime, or was a "mad bomber" intent upon anarchistic mischief. But Forster probably is referring to those kinds of explicit betrayals which involve exposing a friend to embarrassment or punishment for merely standing by a private belief. As such, it expresses a kind of freedom which is often at odds with duty.
The Greene quotation is more personal, referring to the allegiance which an individual makes, privately, to himself. It assumes that such oaths and vows are by their nature secret, never divulged, and that by maintaining a sort of "neutral" ground--a personal code of non-commitment--one may save one's moral soul by never truly (to one's self) taking sides. This kind of alienation from outward forms of connection is typical in the modern world, since it accepts as a given that we all have private lives which are distinct and separate from our existence in the everyday world. It's explicitly immoral, or morally ambiguous, since it sets the individual ethically apart from an expressed, committed choice. Each individual is therefore free to maintain a private code. A private code implies a degree of freedom, a core of sensibility which is impenetrable, even under torture, or extreme temptation. It puts a high degree of value (esteem) upon individual freedom.
It is this internal sense of the self's independence which ultimately guides all our decisions--all our choices and actions. It cannot be bought, or stolen. It exists despite every compromise or betrayal we may commit. In religious terms, it is our redemptive portion, which, despite every sin or evil deed or mistake or accident we may commit, is still within our power to preserve. It's a sort of saving grace. I'm not a theologian, but I suspect that this concept of the inviolable soul is a familiar one to religious historians or theoreticians.
It may be that friendship is the greatest of all possible human relationships, greater than love, greater than patriotism, greater than loyalty to race, sex, religion, family or business. Friendship must be nurtured, and tended, like any living thing. It is voluntary, and therefore enabling and empowering. Woe betide the man or woman who has no friends, or has no use for friendship. He/she is truly alone.