which. the psychologist and ethnologist hold to be a distinctly human trait. Both could have developed only as the power of conceptual thinking advanced. But speech seems to imply the existence of voluntary imitation, whereas the contrary is not necessarily true. The association of a particular sound or even gesture with a particular thing or act is not the only element in speech. There must be the same association in the minds of two or more individuals. The simplest way to account for such similarity of association is by the process of voluntary imitation. Doubtless inarticulate cries became signals arousing alertness to stimulation of various sorts long before voluntary imitation had become well-developed. Instinctive imitation had doubtless also created similar cries under similar circumstances, and nothing more perhaps was needed, in some instances, than the recognition on the part of one of two individuals that both used the same cry under the same circumstances, to produce the communication of an idea. The moment, however, an individual desired to make use of this recognition for the purpose of communicating an idea, he must have used the signal-sound as a model, knowing it to be the sound which the other individual associated with the idea he wished to convey. This purposive repetition of the model-sound involved voluntary imitation whether the model was the idea of another individual's cry or that of his own. It is evident, however, that soon after voluntary imitation appeared speech must have begun to arise. But many advances other than speech must have occurred as soon as voluntary imitation appeared. Long before language could have developed to any great extent man must have begun purposively to imitate things other than cries and gestures. The unskilful hunter must have learned new methods from the skilful. The man who discovered that a club was more effective than a fist soon had many followers making use of his invention. In short, voluntary imitation presently entered into every phase of life wherein it became possible to hand down by a psychological process the pragmatically valuable results of the past experience of the race. As soon as voluntary imitation appeared, therefore, the basis was laid for the continuity of history. Speech accelerated development tremendously, but it may be surmised with a considerable degree of probability that voluntary imitation of useful activities was well advanced before man did much talking that "accomplished things."
Doubtless the development of whatever degree of conceptual thinking is required for voluntary imitation was a long and gradual process. A prior stage in which thought was purely in recepts, to use Romanes' term, must have existed for ages. There may prove to have been other prior advances of an importance equal to that of voluntary imitation, the exact nature of which the observer of animal behavior may yet discover, but whatever may be in store in this field, it is certain that