This speech on the origin of mind is Saayaacchapis’s own elucidation of one of his cherished tupaati, chosen to celebrate his daughter’s metamorphosis and entry into adulthood. It is not by any means the only passage in world literature linking mind and blood. Empedokles, for one, says that heart’s blood is the only real constituent of thought. “I know it in my blood” is also a stock metaphor in English, whose power is long lost through overuse. But we must read these words in context. Here they are tied to a piece of ceremonial theater, which is tied in turn to an event. I know of no philosopher or poet other than Saayaacchapis who finds the origin of mind in self-inflicted male menstruation.

Robert Bringhurst, “The Origin of Mind”, in Everywhere Being Is Dancing: Twenty Pieces of Thinking