The Rebus Breakthrough

The shift from pictographic to phonetic writing was writing's most important leap. Early signs stood for things: a picture of a cow meant cow.

But how do you write abstract ideas like justice, debt, or tomorrow? Sumerian scribes solved this by using signs for their sound values rather than their meanings — a trick called the rebus principle. The sign for arrow (ti) could also mean life (also ti in Sumerian).

This breakthrough, refined over the following centuries, made it possible to write almost any spoken word, opening the door to laws, letters, and eventually literature.