As a matter of fact, quite a number of cases can be given in which convergent evolution, beginning from distinct beginnings, has led to the same results. I have referred before to the instance of primitive art, and have mentioned the theory that geometrical form develops from realistic representations, which lead through symbolic conventionalism to purely æsthetic motives. We may remark here that a great diversity of objects might in this way have given rise to the same decorative motives, so that the survival of the same decorative motive would not lead back to the same realistic origin; but more important than this, we may point out that geometrical motives of the same type have developed from the tendency of the artist to play with his technique as the virtuoso plays on his instrument; that the expert basket-weaver, by varying the arrangement of her weave, was led to the development of geometrical designs of the same form as those that were developed in other places from realistic representations. We may even go a step farther, and recognize that geometrical forms developed from the technique suggested animal forms, which later on were modified so as to assume realistic forms; so that in the case of decorative art the same forms may just as well stand at the beginning of a series of development as at the end (Von den Steinen). Another example may not be amiss. The use of masks is found among a great number of peoples. The origin of the custom is by no means clear in all cases, but a few typical forms of their use may easily be distinguished. They are intended to deceive spirits as to the identity of the wearer, and may thus protect him against attack; or the mask may represent a spirit which is personified by the wearer, who in this way frightens away supernatural enemies. Still other masks are commemorative, the wearer personifying a deceased friend. Masks are also used in theatrical performances illustrating mythological incidents (Andree). While it is not at all necessary to assume that these explanations given by the wearer of masks represent the actual historical development of the custom, the explanations themselves suggest the improbability of a single origin of the custom.