[EAS]Leonardo da Vinci

pjk pjk at design.eng.yale.edu
Mon Jun 2 15:40:02 EDT 2003

Subject:   Leonardo da Vinci

Dear Colleagues -

The NewsScan item below evoked some pleasant memories. Some years ago
I had the pleasure to see the then travelling exhibit "Leonardo and
Renaissance engineers" organized and designed by the Istituto e Museo
di Storia della Scienza of Florence
<http://galileo.imss.fi.it/news/mostra/index.html>, which featured
exquisite wooden models built from the drawings of Brunelleschi,
Taccola, Filarete, Francesco di Giorgio and Leonardo. Drawings were
also on display. One could discuss at some length the necessary
interpretive inventiveness of rendering such drawings into working
models, inventiveness which may have been expected of craftsmen of the
day, much as musicians were expected to add interpretive detail to
sparser written music.

But the feature of the exhibits that most most struck and astonished
me, far beyond any argument about rendering details of the models, was
the difference in conceptualization between Leonardo and his
contemporaries. Whereas the latter would design large complicated
machines for very particular purposes, e.g. a machine for dredging mud
from canals by Francesco di Giorgio, Leonardo's thinking about
mechanisms was based on a more modular approach. Larger machines were
composites of individually distinct concepts, such as converting
rotary into linear motion, reciprocal motion, worm gear, etc. Many of
the Leonardo models represented such basic mechanisms.

The machines of Leonardo's contemporaries seemed inconsistent in their
thinking about mechanical operation, and, complex though they were,
could by the modern eye often immediately be seen as violating basic
principles of mechanical efficiency, creating excessive liability to
stress under load, etc. Most were probably never built in their day,
with the drawings serving as "funding proposals" or "resume" material.

Whether, by their modularity, Leonardo's machines were less liable to
conceptual inconsistencies, more disposed to greater mechanical
efficiency and realizability in materials of the day, I am not
prepared to say, though I am inclined to think so. But Leonardo's
conceptualizing in terms of modules, "sub-systems" making up a larger
"system," which is one of the defining attributes of modern
engineering, that seemed to me abundantly clear.

All best,  -PJK

(from NewsScan Daily, 2 June 2003)

      In his short biography of Leonardo da Vinci, physician and
popular  author Sherwin B. Nuland writes:
      "Leonardo's was a modern mind, the first of its kind that
posterity  can look back on. Like every true scientist of every era,
he was taught by  nature, and determined never consciously to allow
himself to be slave to the thinking of the past. That the past
sometimes entered unknowingly into  his interpretations of what he saw
should not blind us to the detachment with which he attempted to make
his observations. His writings refer only infrequently to the great
men of antiquity. He fought powerfully against the unseen temptations
of his intellectual heritage, and won far more often than he lost.
'Anyone who in discussion relies upon authority uses not his 
understanding but his memory,' he wrote. In the last analysis, he
trusted  only what he could see in his own studies. Those
misinterpretations that inevitably crept into his writings were the
result of an inherited tradition so pervasive that even the thinking
of a genius of such magnitude  could not entirely escape them.
      "Though he has often been called the ultimate Renaissance man,
there is much to be said for the argument that Leonardo was only in
part a man of the Renaissance. While he epitomized the zest for life
and nature that was the guiding theme of humanism, he did at the same
time eschew the  dependence on ancient sources and the worshipful
repetition of its principles that equally characterized its
scholarship. 'Those who study the ancients and not the works of
Nature,' he wrote, 'are stepsons and not sons of Nature, the mother
of all good authors.' He was the first to approach the pronouncements
of the Aristotles, Ptolemys, and Galens as teachings to be tested and
challenged rather than as teachings to be necessarily accepted and
verified. That his basic frame of reference originated in their
writings meant only that he was, indeed, a fallible man of his time; 
some of his greatest errors and missed opportunities resulted from
that background of classical thought which he could not escape. His
astronomy  was largely Ptolemaic and his physiology Galenic. But when
the objectivity of his eye showed him otherwise as he came to
'abundantly appreciate the infinite works of nature,' he did not
hesitate to say so. And this is why we find in one of his notebooks
such jots as a statement astonishing for its time: 'The sun does not
move.' As his ultimate direction was to question the heritage of
earlier ages and seek only the truth of his own experience, he was
able to blaze new paths through territories that his contemporaries
believed to have been correctly charted long before their time."
for Sherwin B. Nuland's "Leonardo da Vinci" -- or look for it in your 
favorite library. (We donate all revenue from our book recommendations
to  adult literacy programs.)

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