Therefore it is, that many small items of ethnic knowledge acquire considerable importance. From the average man’s point of view, it is of little moment that the Zuñi farm and the Yurok and Nootka do not, or that the former refuse to marry their dead wives’ sisters and the latter insist on it. At best, such bits of facts have for the layman only the interest of idle curiosities, of antiquarian fragments. To the specialist, however, they become dependable means to a useful end, much as intimate knowledge of the position of arteries and nerves serves the surgeon.