Writing has two advantages over spoken language; it can be transported over distance and it persists over time. The first advantage became necessary only where large populations with a common language began to spread over a large area. Small groups don’t need to communicate over long distances, so they don’t need writing. Writing was first developed for purely practical purposes. When you sent so many bushels of wheat to a distant city in trade or as taxes in kind, you pressed symbols for wheat and the amount on a clay tablet and pressed your personal seal on the bottom. The receiver now had a record of what had been sent and would know if anything had been pilfered along the way. Because writing persists in time, those who collected large amounts of commodities year after year, i.e. the king’s tax collectors, could keep a running record of what had been collected and what was owed. This bookkeeping writing flowered into phonetic alphabets and the vastly varied types of literature we enjoy today.