In the most remote recorded times, he argues, it was debt, rather than money, that made society hum. The majority of cuneiform documents we have from ancient Mesopotamia relate to financial matters, and they show that by about 3500 BC the Sumerians had a uniform system of accountancy, the silver shekel. However, Graeber asserts, this denomination was less money in our modern sense (it hardly circulated) than a way for accountants to keep track of who owed what to whom. Debt, in other words, was the basic currency that got business done. Money of the portable kind emerged later, primarily in times and areas of conflict, when grab-and-go was a priority. As civilization advanced and spread, systems where debt was central and instrumental to economic activity emerged in the Islamic world, India, China, and throughout the Mediterranean.
Graeber also outlines the important role that debt forgiveness has played, historically, in curbing runaway debt and out-of-control usury. Harsh penalties for debts tend to hurt the lowest strata of society, and in ancient times, could end in enslavement or worse – taking a very dynamic element of the economy out of the equation. So rulers in a number of places, until about the Enlightenment, often established safeguarding systems that protected debtors rather than lenders.
h/t James Choi