Underground Rivers - University of New Mexico

Chapter 7 -- The Concept of Circulation
The Florentine polymath Leonardo da Vinci (1452-1519) merits
centerpiece status in our underground sojourn if for no other reason than
his encyclopedic curiosity. Da Vinci’s “primo motore” lies squarely within
the Christian god's perceived role for the era. Da Vinci's doctrinal dues
thus paid, he was somewhat of a pantheist, largely excluding the divine
from his musings. Aristotle would have concurred.
The circa 1513 sketch shows the
elder artist pondering the flow of
water. The backwards-inscribed
text reads,
Observe the motion of the
surface of the water, how it
resembles that of hair, which
has two motions -- one
depends on the weight of the
hair, the other on the direction
of the curls; thus the water
forms whirling eddies, one part
following the impetus of the
chief current, and the other
following the incidental motion
and return flow.
Despite da Vinci’s oft-cited, “In talking about water, remember to call upon experiment and then
on reasoning,” rarely, if ever, did he subject his concepts to physical test, again falling in with
Aristotle. Da Vinci honored the here-and-now, but not to the point of getting his hands wet.
But da Vinci's experimental shortcoming didn't inhibit his greatest strength. "Do you not see that
the eye embraces the beauty of the whole world?" The visual is pre-eminently the real. What da
Vinci saw he never doubted -- Aristotelian to the fullest.
To da Vinci, water is "il vetturale di natura," the vehicle of nature. In his First Book on Water (one
of his few manuscripts written thematically, not as happenstance observations), da Vinci writes.
Water is sometimes sharp and sometimes strong,
sometimes acid and sometimes bitter,
sometimes sweet and sometimes thick or thin,
sometimes seen bringing hurt or pestilence,
sometimes health-giving and sometimes poisonous.
It suffers change into as many natures as are the different places through which it passes.
Unfortunately for focused scholarship, da Vinci's "many places" was indeed many.
If you chose to say that the rains of the winter or the melting of the snows in summer were the
cause of the birth of rivers, I could mention the rivers which originate in the torrid countries of
Africa, where it never rains -- and still less snows -- because the intense heat always melts into
air all the clouds which are borne thither by the winds.
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