It may be pointed out, in passing, that many animals have not been domesticated even at this late day--such as the tiger, the eagle and the bear. But, equally, certain tribes of men have not been domesticated. It may be that in both the undomesticated men and the undomesticated brutes, the mind is of such a character that it cannot assimilate even the first grains of knowledge, or make any effort whatever of an inventive character. There was one invention that was probably made in the Old Stone Age, which must have needed considerable inventiveness to be developed as highly as it was developed during the Old and New Stone Ages, and that was language. The origin of language is, of course, hidden in the impenetrable mystery of the childhood of the race; and it may be that language was an original attribute of man. If we reason, however, that the development of language must have been a continuing act from the first, inferring it from the fact that it has been a continuing act from the dawn of recorded history until now, and if we suppose that it had a rise and a growth like those of other arts, we may reasonably conclude that some man invented the plan of making his wants known by the use of vocal sounds, uttered in accordance with a preconcerted code; that the invention was only partially successful at first, and that it was afterwards improved. That language was not a natural gift, but rather the result of an invention and subsequent development, is suggested by the fact that a child has to be taught to speak, but does not have to be taught to exercise his natural functions, such as breathing, eating, drinking, walking, etc. Which was the first invention ever made by man, there is, of course, no means of ascertaining; but it seems obvious that that of language must have been among the first. The invention of weapons we may easily imagine to have been actually the first, called for by the necessity of defense against wild beasts and other men. Following the defense by individual men of their individual lives, it seems logical to suppose that a man and his wife, a man and his brother, and then groups of men, banded together in their common defense against common foes. To further their joint action, what would be more valuable than a language consisting of vocal sounds, arranged in accordance with a simple code, as a means of conveying information, issuing warnings, and giving signals in emergencies, to insure concerted action? That language should later be used for manifold other purposes would be most natural; for many other arts have been invented primarily to further man's first aim, the preservation of his life, and have afterwards been employed for other purposes. The uses of clothing, houses, knives, guns and of nearly all weapons are cases in point.