When one speaks of tradition, that is to say, of the transmission of human knowledge from one generation to another, one implies that there are two methods by which that transmission is effected—the spoken and the written word; thus one draws a distinction between oral and written tradition.

Nowadays written tradition alone is of importance; but one recognizes that it has gradually replaced that oral tradition which alone existed, as one supposes, in prehistoric times. We wish here to call attention to yet another mode of transmission which certainly played a part, perhaps even an important part, in the Stone Ages, and disregard of which might in certain instances seriously confuse the study of prehistoric archaeology.