"Beginning in the pottery-phase of the Neolithic, clay tokens are widely attested as a system of counting and identifying specific amounts of specified livestock or commodities. The tokens, enclosed in clay envelopes after being impressed on their rounded surface, were gradually replaced by impressions on flat or plano-convex tablets, and these in turn by more or less conventionalized pictures of the tokens incised on the clay with a reed stylus. That final step completed the transition to full writing, and with it the consequent ability to record contemporary events for posterity".Hallo, W.; Simpson, W. (). The Ancient Near East. New York: Harcourt, Brace, Jovanovich. p.25.