We have already spoken of the library of Asshurbanipal, or the Ninevan library, and have seen what a world of light was thrown upon Assyrian civilization when its surviving tablets were at last deciphered. Babylonia maintained libraries, however, before Nineveh was founded. These clustered, for reasons which we shall soon see, around the temples. At Erech were early collected writings which were concerned with the religion of the ancient Chaldeans, together with the myths and legends of the country. So many tablets were preserved in this temple that Erech was called the "city of books." A library, rich in mathematical lore, grew up at Larsa, another at Nippur, and still another at Cathah. Smaller libraries were attached to all the great temples. When we speak of "libraries" in Mesopotamia, collections of clay tablets are meant. Rooms were frequently provided within the temples for the storing of these clay books. The size of the tablet varied greatly. The largest were flat and about 9 by 6-1/2 inches; smaller ones were slightly convex, while tiny ones, not more than one inch long, containing but a line or two, have been found. Sometimes the lettering is so fine that it could have been done only with the aid of a lens, and it cannot be read without one. In these valleys, the cheapest, most available writing material was the soft clay, ever in evidence. When bricks had been partially dried in the sun, a substance was formed which readily received impressions, and these became firm as the tablet hardened. Both sides and sometimes the edges as well, were written upon, and little pegs of wood provided legs for the brick to rest upon when reversed, that the soft impressions might not be injured. To make the whole proof against fire and water, it was finally baked in an oven. When so treated, a material was made which proved more enduring against action of the elements than either parchment or papyrus. It is quite certain that papyrus and possibly parchment as well were used for writing purposes, especially in the later period, but no fragment of either has survived. Certain disadvantages attached to the cheap tablets. They were heavy and unwieldy to hold or carry, but more especially, they allowed no embellishments or lengthy descriptions. Owing to the laborious method of transcribing records, everything was of necessity abbreviated and simplified. Thus we see how one thing acts upon another--the country afforded only clay tablets for writing material; these, limited because of size and weight, curtailed speech and so influenced the style of expression.