The invention and spread of coin money in the Greek world, in the sixth century bce, had far-reaching consequences for the Greek conceptualization of friendship (philia). From the Dark Ages onwards, long-term interpersonal bonds are predominantly conceived in terms of the reciprocal exchange of favors and benefits—exchanges that create lasting ties of gratitude and obligation.
However, the increasing monetization of the Greek economy and Greek thought at large, produces a new notion of mutuality that rapidly becomes more and more prevalent in popular thought: the commercial transaction, i.e., the simultaneous exchange of equivalent goods that does not necessarily yield a lasting relationship between the participants. Reciprocal exchanges become potentially ambivalent, allowing for multiple, sometimes conflicting interpretations of the same exchanges.
The demarcation problems caused by this ambiguity provoke new cultural constructions of reciprocity in friendship as distinct from, opposed to, compatible with or reducible to monetary transaction.