This program sums up the evolution of commerce, from barter, to coinage, to today’s stock market. Economist Professor Grantham, of McGill University, discusses how writing and accounting facilitated trade and gave rise to a merchant class in the ancient world, and hence the spread of classical civilization in the Mediterranean and Asia Minor, culminating in the Roman Empire. The importance of the spice and silk trades is also discussed, along with how the quest for new trading partners impelled exploration in the 15th and 16th centuries, leading to the discovery of the New World and new prosperity. (53 minutes)