Clay tablets were flattened pieces of clay some small enough to be held in the palm of the hand on which the scribe embossed with the stylus. Then the tablets would be left to dry. A permanent record had been created that survived millennia of natural erosion and human destruction.
In place after place in centers of commerce and administration in temples and palaces there were State and private archives full of such tablets; and there were actual libraries where the tablets ten of thousands of them were neatly arranged by subject, their content entitled, their scribe named, their sequel numbered.
Invariably whenever they dealt with history or science, or the God’s, they were identified as copies of earliest tablets in the older language.