KIM MacQUARRIE from The Last Days of the Incas: "The Spaniards, meanwhile, still had a very weak grasp of just how complex the empire that they had only partially conquered was. While they had immediately recognized the overall similarities with the Old World's culture of kings, nobles, priests, and commoners, they knew little of the actual mechanisms that enabled the Inca Empire to function. The Inca's genius -- like that of the Romans -- lay in their masterful organizational abilities. Amazingly, an ethnic group that probably never exceeded 100,000 individuals was able to regulate the activities of roughly ten million people. This was in spite of the fact that the empire's citizens spoke more than seven hundred local languages and were distributed among thousands of miles of some of the most rugged and diverse terrain on earth."
PHOTOGRAPHER'S JOURNAL ("Why Here," part 13): At the end of our first day at Machu Picchu, our only evening, I took a long walk alone to a spot called the Inca Bridge where the Incas had thrown a removable catwalk of logs, a drawbridge, between two parts of the trail and across a face of sheer, verticle rock. The trail was part of one of the two Inca roads into the city. It hugged a jungle cliff, high along the west side of the mountain, above the Urubamba. Among their other achievements at the time Pizarro arrived in Peru, the Incas had paved 10,000 miles of road like this to knit their empire together.
Roads and runners were enough. With only knotted chords to record their figures, local chiefs, warlords, and administrators rendered population-based taxes, usually in labor, to the king and his administrators. The taxes built an agricultural surplus that fed the nation and filled emergency warehouses. Did the terms of the social compact protect every citizen from times of drought and famine? How might such compassion be squared with the ruthless and brutal tyranny for which Atahualpa was also known? What kind of paternal justice balanced the well-being of the Inca nation and the well-being of each of its citizens? Whatever the case, it seems Inca administration had been bountiful, even after some years of civil war.
The Inca drawbridge was a simple defensive device, but its effectiveness depended on an alert guard and his absolutely superior vantage point that prevented anyone from getting near the bridged gap without being exposed and vulnerable. The Inca's, was a labor-driven economy.