Friendship is composed of a single soul inhabiting two bodies.

The line expresses an ideal of friendship as profound unity: two distinct persons so aligned in character, purpose, and affection that they seem animated by one shared inner life. It elevates friendship beyond utility or pleasure into a moral and spiritual concord—an image of mutual understanding, loyalty, and self-extension, where the friend becomes “another self.” The metaphor also implies reciprocity and equality: the “single soul” is not possessed by one party but jointly “inhabits” both, suggesting that true friendship dissolves isolation without erasing individuality. In later reception, the sentiment became a standard classical topos for perfect friendship and was often cited to praise intimate bonds.

Commonly attributed instead to Aristotle (often rendered as “a single soul dwelling in two bodies” or “one soul inhabiting two bodies”); also frequently paraphrased as “Friendship is one mind in two bodies.”