In the concluding chapter of this volume an estimate is given to the extent to which Sumerian culture influenced, either directly or indirectly, other races in Asia, Egypt, and the West. In such matters the interest attaching to the Sumerian original is largely derived from its effects, and its study may be undertaken mainly with the view of elucidating a later development. But one department of Sumerian activity forms a striking exception to this rule. The arts of sculpture and engraving, as practised by the Sumerians, are well worthy of study on their own account, for while their work in all periods is marked by spirit and originality, that of the later time reaches a remarkable standard of excellence. The improvement in technique observable in the later period may largely be due to the influence of Semitic work, which was derived from Sumer and reacted in its turn on the parent stem. But the original impulse to artistic production was of purely Sumerian origin, and it is possible to trace the gradual development of its products from the rudest reliefs of the archaic period to the finished sculpture of Gudea's reign.[21] The character of the Semitic art of Akkad was secondary and derivative, though the Semites certainly improved on what they borrowed; in that of the Sumerians the seeds of its later excellence may be detected from the beginning. The most ancient of the sculptured reliefs of the Sumerians are very rudely cut, and their age is attested not only by their primitive character, but also by the linear form of the writing which is found upon them. These, owing to their smaller size, are the best preserved, for the later reliefs, which belong to the period when Sumerian art reached its fullest development, are unfortunately represented only by fragments. But they suffice to show the spirit which animated these ancient craftsmen, and enabled them successfully to overcome difficulties of technique which were carefully avoided by the later sculptors of Assyria. To take a single instance, we may note the manner in which they represented the heads of the principal figures of a composition in full-face, and did not seek to avoid the difficulty of foreshortening the features by a monotonous arrangement in profile. A good example of their bolder method of composition is afforded by the relief of a god, generally identified with Ningirsu, which dates from the epoch of Gudea; he is seated upon a throne, and while the torso and bearded head are sculptured full-face, the legs are in profile.[22] On another fragment of a relief of the same period, beautifully cut in alabaster but much damaged by fire, a goddess is represented seated on the knees of a god. The rendering of the group is very spirited, for while the god gazes in profile at his wife, she looks out from the sculpture curving her body from the hips.[23]