I will speak to you about the hau…The hau is not the wind that blows – not at all. Let us suppose that you possess a certain article (taonga) and that you give me this article. You give it to me without setting a price on it. We strike no bargain about it. Now, I give this article to a third person who, after a certain lapse of time, decides to give me something as payment in return (utu). He makes a present to me of something (taonga). Now, this taonga that he gives me is the spirit (hau) of the taonga that I had received from you and that I had given to him. The taonga that I received for these taonga (which came from you) must be returned to you. It would not be fair (tika) on my part to keep these taonga for myself, whether they were desirable (rawe) or undesirable (kino). I must give them to you because they are a hau of the taonga that you gave me. If I kept this other taonga for myself, serious harm might befall me, even death. This is the nature of the hau, the hau of personal property, the hau of the taonga, the hau of the forest. Kati ena
(But enough on this subject).
From Marcel Mauss. The Gift.