The One-to-One Law in Friendship
Friendship may be said to require natures so rare and costly, each so well-tempered, and so happily adapted, and withal so circumstanced, (for even in that particular, a poet says, love demands that the parties be altogether paired,) that its satisfaction can very seldom be assured. It cannot subsist in its perfection, say some of those who are learned in this warm lore of the heart, betwixt more than two. I am not quite so strict in my terms, perhaps because I have never known so high a fellowship as others. I please my imagination more with a circle of godlike men and women variously related to each other, and between whom subsists a lofty intelligence. But I find this law of one to one, peremptory for conversation, which is the practice and consummation of friendship. Do not mix waters too much. The best mix as ill as good and bad. You shall have very useful and cheering discourse at several times with two several men, but let all three of you come together, and you shall not have one new and hearty word. Two may talk and one may hear, but three cannot take part in a conversation of the most sincere and searching sort.
In good company there is never such discourse between two, across the table, as takes place when you leave them alone. In good company, the individuals at once merge their egotism into a social soul exactly co-extensive with the several consciousnesses there present. No partialities of friend to friend, no fondnesses of brother to sister, of wife to husband, are there pertinent, but quite otherwise. Only he may then speak who can sail on the common thought of the party, and not poorly limited to his own. Now this convention, which good sense demands, destroys the high freedom of great conversation, which requires an absolute running of two souls into one.
Ralph Waldo Emerson, in "Essays - Friendship"