Responsive to the ever-changing conditions of life, the necessities of mankind were constantly increasing. His higher intelligence also created a greater diversity of interests, and consequently demanded a fuller and more expressive vehicle of communication for his thoughts. No longer content with what was only needful for the maintenance of social or commercial intercourse, he sought to add to the archaic simplicity of his drawings, skilful arrangement, and a certain degree of artistic feeling and interpretation. It was as though some transitory flashes of artistic power in the minds of prehistoric artists were struggling with an inability to give adequate expression to their inceptions. Their productions, some of them dating from the Palaeolithic and Neolithic periods, were not pretentious works of art. Their primary purpose being representative, their merit was, of course, decided by the success or failure of such representation, apart from any artistic qualities they might possess. =A Distinct Purpose.=--The evident care with which many of the ancient incised drawings or engravings were executed and preserved, together with the permanent character of the materials employed, seems to indicate that these simple yet graphic representations were produced with the distinct purpose of perpetuating a memory as well as for the amplification of a meagre language,--a purpose which considerably enhances their interest, and suggests that the primeval engraver appreciated some at least of the possibilities of his art. Moreover, they frequently possess an intense veracity and directness of imitation which renders them of inestimable value as reliable historical records. Had caprice alone directed the artist's efforts, they would not in so many instances have merited the interest and approval which they now receive. Such, then, were the beginnings of an art that subsequently reached its maturity only by a slow growth of gradual development, and "which, in the modesty and seriousness of its earlier manifestations, is at least as interesting as in the audacity of its later and more impressionistic phases." Engraving as a reproductive as well as an ornamental art was at different periods modified in accordance with ever-changing conditions produced by the exigencies of national and industrial policy. Its frequent adaptation to the various circumstances with which it was indissolubly associated, and the fluctuations of an enthusiasm which was more or less dependent upon national as well as social prosperity, fully justifies the statement that "its history is the mirror of a nation's progress."