Cuneiform writing appears to have been originally inscribed upon a vegetable substance called _likhusi_, but the abundant clay of the alluvial country afforded material whose convenience and permanence brought it into general use. Upon this the characters were impressed by a reed or square-shaped stylus, the clay-books being afterwards baked or sun-dried. For inscriptions on stone or metal a chisel was used. The writing of the Assyrian scribes is often exceedingly minute, the tablets containing a mass of matter in a tiny space. The work was trying enough to sometimes require the use of a magnifying-glass, and among Sir Austin Layard's discoveries at Nineveh was that of a lathe-turned crystal lens which was probably used for the purpose. Obviously the substances chosen account for the angular form of the characters; as the dyer's hand is "subdued to what it works in," so the nature of the material in which the sculptor seeks to express his conceptions largely determines for him the limits of that expression. Phidias himself could not have produced his Pallas Athene from the stubborn granite of Syene; and, as the outcome of the Egyptian temperament, the sphinxes of the Nile valley might have worn a less relentless look had they been fashioned of the marble of Pentelicus. Much as the abrupt cuneiform character tends, however, to obscure the traces of its derivation, there are sufficing proofs that it is of pictographic origin, although no examples of picture-writing in Mesopotamia corresponding in primitiveness to those already given from barbaric sources have been discovered. In the linear Babylonian, as it is called, the hieroglyph for "sun" is a diamond-shaped figure [Symbol] which later on became [Symbol], and in the latest cuneiform, [Symbol]. Evidently the earliest sign was a circle, which could not be easily traced on the stone or clay, and hence appears as the angular character shown above. The annexed table, which is a copy of one supplied by Mr. Pinches to Professor Keane, and published in his admirable monograph, _Man Past and Present_, gives a set of typical examples of the derivation of cuneiform characters from the earliest known pictographs. EVOLUTION OF THE AKKADIAN CUNEIFORMS. 1000 B.C. About 2500 Oldest known line forms, and later. to 1500 B.C. 3000 B.C. and earlier.