Just something I've been pondering since reading it a week or so ago...

"When is a gift not a gift, but a contractual obligation? First, for a gift to be authentic, there must be a delay in return. To return a gift straight away implies a lack of gratitude, a desire to discharge an obligation as soon as possible because the original gift was not really welcomed. Thus, to be invited to dinner is to receive the gift of hospitality. To return the invitation the next day, to have those people back to dinner tomorrow, is insulting: it implies that the gift imposed a debt which must be discharged immediately because continuing relationship is, at best, of no significance, and at worst positively unwelcome.

The second feature of an authentic gift, as opposed to a binding contract, is that the gift given back must be different, and not obviously equivalent. To return the gift of a record of a certain artist with the self-same recording seems strange, or to respond to a gift of flowers with the giving of a similar bouquet implies that the first gift was not, perhaps, welcome."