My favorite invention in all of history is the sail. I love sailing for pleasure but this invention is serious business. Since the first recorded use of sails to power watercraft by the Egyptians and the Sumerians in about 3200 BCE the sail has enabled trade and communications between peoples of previously remote locations. The value of this mode of transport is quite evident because of the great wealth amassed by traders and the growing wealth of cities. The hidden benefit was the spread of ideas which hitched a ride with the sailors as they set up communication networks that followed the path of the trade.