As early as the ninth century B.C. the Assyrians had developed the art of sculpture in bas-relief in a way that constituted a marvellous advance upon anything that may reasonably be believed to have been performed by prehistoric man, and only three centuries later came the culminating period of Greek art, which marked the stage of almost revolutionary progress. _Ninth. The Art of Writing._ One other art remains to be mentioned even in the most cursory survey. This is the latest, and in some respects the greatest of them all--the art of writing. In one sense this art is only a development of the art of drawing, but it is a development that has such momentous consequences that it may well be considered as distinct. Moreover, it led to results so important for the historian, and so directly in line of all our future studies, that we shall do well to examine it somewhat more in detail. All the various phases of prehistoric culture at which we have just glanced have left reminiscences, more or less vague in character, for the guidance of students of later ages; but the materials for history proper only began to be accumulated after man had learned to give tangible expression to his thoughts in written words. No doubt the first steps toward this accomplishment were taken at a very early day. We have seen that the cave-dweller even made graphic though crude pictures, including hunting scenes, that are in effect the same in intent, and up to a certain point the same in result, as if the features of the event were described in words. Doubtless there was no generation after the stone age in which men did not resort, more or less, to the graphic delineation of ideas.