The series of models presented in the foregoing chapters have successively been more abstractly constructed, and more and more remote from the physical world exemplified by the activities of copulation and birth. It may be salutary to end this collection of essays with a reference to a process working in the opposite direction, a process of deconstruction (in a simpler sense than is now fashionable) rather than construction, of forgetting rather than remembering. The following brief statement of what I called structural amnesia is taken from my first professional published paper, dealing with the collection of genealogies in an African matrilineal society. It appeared in 1947 in a journal now hard to find. It is appropriate, I suppose, that the source for a principle of amnesia should itself be forgotten, but I think that the principle is worth re-stating.