Some examples might help. Consider the flow of blood through the body
and the circulation of traffic in the city. Richard Sennett has described
the revolution in images of the body that came with the publication of
William Harvey’s De motu cordis in 1628. It was in this text that Harvey
announced his discovery that the heart pumps blood through the arteries
around the body—blood which is then returned to the heart by the veins.
He had discovered the body’s circulation system. In so doing he prompted
others to see the body in similar ways. Th us, Thomas Willis began to
suggest the presence of the nervous system. “The mechanical movement in
the body, nervous movements as well as the movements of blood, created
a more secular understanding of the body in contesting the ancient notion
that the soul (the anima) is the source of life’s energy.” Now it was not the
soul that energized life in the body, but the blood. Blood was, for Harvey,
“life itself.” Clearly, Harvey’s discovery had momentous implications
for the study of the body and for the history of human medicine, but its
implications were much wider than that. Ideas about mobility in the sphere
of the body were quickly translated into areas such as economics and city
planning.