or commercial operations, and to send that information to other places. These calculi are perhaps the same type as the tokens found on sites in the Near East for the next few thousand years, whose function remains uncertain. It is thought that notches would be placed on the surface of the clay balls containing the calculi, leading to the creation of numerical tablets which served as an aide-mémoire before the development of true writing (on which, see below). The development of writing, whether or not it derived from accounting practices, represented a new management tool which made it possible to note information more precisely and for a longer-term. The development of these administrative practices necessitated the development of a system of measurement which varied depending on what they were to measure (animals, workers, wool, grain, tools, pottery, surfaces, etc.). They are very diverse: some use a sexagesimal system (base 60), which would become the universal system in subsequent periods, but others employ a decimal system (base 10) or even a mixed system called 'bisexagesimal', all of which makes it more difficult to understand the texts. The system for counting time was also developed by the scribes of institutions in the Late Uruk period. Intellectual and symbolic life The developments that society experienced in the Uruk period had an impact in the mental and symbolic realm which manifested as a number of different phenomena. First, although the appearance of writing was undoubtedly connected to the managerial needs of the first state, it led to profound intellectual changes. Art also reflected a society more heavily shaped by political power, and religious cults grew more impressive and spectacular than previously. The development of religious thought in this period remains very poorly understood. Writing Writing appeared very early in the Middle Uruk period, and then developed further in the Late Uruk and Jemdet Nasr periods. The first clay tablets inscribed with a reed stylus are found in Uruk IV (nearly 2000 tablets were found in the Eanna quarter) and some are found also in Susa II, consisting solely of numeric signs. For the Jemdet Nasr period, there is more evidence from more sites: the majority come from Uruk III (around 3000 tablets), but also Jemdet Nasr, Tell Uqair, Umma, Khafadje, Tell Asmar, Nineveh, Tell Brak, Habuba Kabira, etc. as well as tablets with proto-Elamite writing in Iran (especially Susa), the second writing system to