What does anthropology say?

Anthropology offers no model of “the gift” and provides no single definition, but it alerts us to the dynamics of reciprocity, power, and obligation that have been common in gift-relations, but are easily missed or misconstrued. Studies of gift-giving in pre-modern societies are of particular heuristic value in raising questions worth testing against ancient sources.—J. M. G. Barclay, Paul and the Gift, 183