Greeks and Romans were notorious in their disdain for technology. Aristotle noted that to be engaged in the mechanical arts was "illiberal and irksome." Seneca infamously characterized invention as something fit only for "the meanest slaves." The Roman Emperor Vespasian rejected technological innovation for fear that it would lead to unemployment.
Greek and Roman economies were built on slavery. Strabo described the slave market at Delos as capable of handling the sale of 10,000 slaves a day. With an abundant supply of manual labor, the Romans had little incentive to develop artificial or mechanical power sources. Technical occupations such as blacksmithing came to be associated with the lower classes.
With the collapse of the Western Roman Empire in the fifth century AD, a Dark Age in philosophy and science descended upon the Mediterranean region. But the unwritten history of technological progress continued. In northern and western Europe, there was never a period of regression. As early as 370 AD, an unknown author noted the "mechanical inventiveness" of the "barbarian peoples" of northern Europe. The Christian ethic of universal brotherhood slowly spread through Europe, and slavery began to disappear. Tribes and peoples became united under a common creed. Europeans not only embraced technology, but they also developed the idea of a universal society based upon respect for the dignity and worth of the individual human being.
From the sixth through the ninth centuries AD, Europeans adopted new agricultural technologies that dramatically increased productivity. One of these innovations was a heavy wheeled plow that broke up the soil more efficiently than the Roman "scratch" plow. Formerly unproductive lands were transformed into arable cropland.
The Greeks and Romans had harnessed horses with a throat-and-girth harness that consisted of a strap placed across the animal's neck. As soon as the horse began to pull, he would choke himself. In the ninth century, Europeans began to use a padded horse collar that transferred the load of a draught animal to its shoulders. Horses harnessed with collars were able to pull four to five times more weight than those with throat-and-girth harnesses.
Horse power was also facilitated by the introduction of the iron shoe. With fast-moving horses harnessed efficiently, it became possible to transport goods up to 35 kilometers in one day if a sufficiently good road was available. There was now a way to dispose of agricultural surpluses and create wealth that could be used for investment in technology and infrastructure. Thus, the introduction of the lowly horseshoe and collar fostered commerce, civilization, and the growth of towns.
Under the Roman system of two-field crop rotation, half the land was left fallow and unproductive at any given time. In the eighth century, Europeans began to practice three-field crop rotation. Fields lay fallow for only a third of the year, and grains were alternated with legumes that enriched the soil with nitrogen. The cultivation of legumes such as peas and beans added valuable protein to European diets.
In the tenth century, the climate began to warm, and Europe entered the High Middle Ages. By the thirteenth century, the new agricultural technologies had doubled per acre yields....