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Andreas Vesalius: Reformer or Revolutionary?
Excerpts from Revolution in Science (1985)
by I. Bernard Cohen
Andreas Vesalius (1514-1564), founder of modern
anatomical science, published his great book, De
Humani Corporis Fabrica (On the Construction of
the Human Body), in the same year, 1543, that
saw the appearance of Copernicus’s De
Revolutionibus. At the time of publication Vesalius
was still a young man, in his prime years, while
Copernicus was elderly and in fact at the point of
death. Vesalius’s ability was recognized at the
very start of his career; he received his M.D.
magna cum laude from the University of Padua on
5 December 1537 at the age of twenty-three, and
on the following day was appointed explicator
chirurgiae and began to give lectures to medical
students on surgery and anatomy. From the start
he showed his independence, for in his annual
anatomical lectures and demonstrations—which
were still “Galenic in character”—he broke with
tradition and, “contrary to custom… performed the
dissections rather than consigning that task to a
surgeon.” A year later, in 1538, Vesalius
published two works. One was the set of anatomical drawings known as Tabulae
Anatomica Sex or Six Anatomical Plates. The other was “a revised and augmented
edition” of the Galenically oriented manual of dissection of a former teacher, an edition
notable for Vesalius’s own “independent anatomical judgments”… In 1539, it was officially
recorded that this brilliant anatomist and lecturer “had aroused very great admiration in
all the students.”
In that same year, the judge of the Paduan criminal court turned over to Vesalius for
anatomical study the corpses of executed criminals. With a sufficient supply of human
bodies to dissect, Vesalius now made great progress in human anatomy and “became
increasingly convinced that Galen’s description of human anatomy was
basically an account of the anatomy of animals in general and was often
erroneous insofar as the human body was concerned.” By the end of 1539 he was
able to announce publicly in Padua and also in Bologna… that the only way to learn the
anatomy of the human body was by direct dissection and observation and not by reading
books. He compared and contrasted an articulated human skeleton and the skeleton of
an ape or a monkey to prove without any possibility of doubt that Galen’s account of
bones was based largely on apes and not humans. Furthermore, as Vesalius said in the
preface to De Fabrica, there are “many incorrect observations… in Galen, even regarding
his monkeys.” Since, in those days, Galen was the respected and unquestioned authority
on every aspect of medical science and practice, Vesalius’s bold challenge must surely be
considered an act of revolt. But was it the first step of a revolution?
Vesalius’s magnum opus, De Humani Corporis Fabrica, was a massive folio volume
embellished by a large number of extraordinary plates that represent a high point in
the use of art to represent scientific knowledge. They are as exciting to contemplate
today as they were some four and a half centuries ago. Vesalius’s subsequent role in
advancing anatomical science as such may have been lessened by the fact that almost
immediately after the publication of his book he gave up the academic life and abandoned
his anatomical studies…. [He] resigned his teaching post and entered medical practice as
a physician to the “imperial household” of Emperor Charles V. When Charles V abdicated
in 1555, Vesalius remained in Spain and became a court physician for Charles’s son, Philip
II. In 1564 he left Spain on a pilgrimage to the Holy Land and—apparently—died on the
way home on the Greek island of Zanthos…
Vesalius’s aim was to convince doctors and anatomists of the inadequacy and even falsity
of the current Galenic anatomy and thus to institute a reform of the subject, which at
the time—he said—was taught in such a way that there was “very little offered to the
students that could not be better taught by a butcher in his shop.” A true anatomy,
based on dissection, was in his opinion the only solid foundation for all of
medicine… Vesalius not only sought graphically and verbally to correct the errors of
Galen but also argued that every medical student and physician should personally base
his knowledge of the human body on direct dissection… In one of the most striking
passages in his book, Vesalius explained how and why the failure of doctors to do their
own anatomies had caused the science of medicine to decline.
In older or classical Latin, the nearest expression to what we today mean by a
revolution is ‘novae res’ (literally, ‘new things’). There were of course a number of new
things in Vesalius’s De Fabrica, any of which contradicted Galen’s statements or accepted
views. It was also definitely new and unheard of to base anatomical knowledge
on the direct experience of human dissection and on dissections of the bodies of
animals for comparative purposes, and to exhort all medical students, anatomical
scientists, and doctors to perform their own dissections of the human body. Not only did
Vesalius show by examples that such actual dissections had produced new knowledge; he
also gave explicit directions as to how the reader should proceed in making a dissection
so as either to verify Vesalius’s own presentation or to “arrive at an independent
conclusion.” This revolutionary aspect of Vesalius’s book was enhanced by the beautiful
and detailed artistic anatomical illustrations. And it was to emphasize the revolutionary
exhortation to “do it yourself” that Vesalius even included a plate showing the tools
needed to carry out the dissections he recommended that the reader perform.
There can be no doubt that Vesalius successfully inaugurated a reform of the
subject of anatomy and the method of teaching it…. [However] historians of
science… [do not] write of a ‘Vesalian revolution’, even though his solid
accomplishments and direct influence in changing his subject would seem more
appropriately to merit such a designation than the alleged reform of astronomy
epitomized in the commonly used expression ‘the Copernican revolution’….
In his published writings, it is not his [Vesalius’s] manner to make a frontal attack on
Galen or Galenic doctrines, nor to criticize or correct Galen, except in specific cases “when
he felt the facts warranted such action.” He “never went out of his way to do so” and
never would have held up Galen to ridicule or “have made a public example” of him.
Vesalius did not assume a revolutionary anti-Galenic posture. He hesitated a
long time before making a public expression of any disagreement with the teachings of
Galen, and when he finally did so he criticized only Galen’s writings on anatomy
and not “the Galenic system of medicine as a whole.” Although Vesalius stoutly criticized
the followers of Galen who never departed “from him by so much as the breadth of a
nail”, Vesalius added at once that he himself would not wish to appear “disloyal to the
author of all good things and lacking in respect for his authority.”… This attitude may be
contrasted with that of the rebel Paracelsus, who publicly cast the medical works of
Avicenna into the burning flames as a declaration of their total lack of worth.
This non-revolutionary attitude of Vesalius may be seen most clearly in his
discussion of the pores alleged to exist in the septum (wall) separating the right
ventricle of the heart from the left. These pores, or passages, were an essential part of
Galenic physiology, providing a necessary pathway for the blood to ooze a drop at a time
from the so-called ‘arterial vein’ (for us, the pulmonary artery) into the ‘venal artery’ (or
pulmonary vein). Galen taught (and Galenists believed) that air is carried to the heart
from the lungs by means of this ‘venal artery’, where it combines to produce arterial
blood. We know today that there are no such pores leading from the right ventricle into
the left (or vice versa), although there are tiny pits on the septum that separate the
ventricles. But these are blind pits; and “even a fine bristle cannot be made to penetrate
from one ventricle to the other.”…
That there are no such passages going from one side of the heart to the other was at
once made evident to Vesalius by actual dissections of the human heart. A true
revolutionary would, I believe, have simply concluded that the whole Galenic physiology,
and perhaps even the Galenic medicine based on it, must be false and should be cast out
at once as having no foundation in fact. But not Vesalius! Instead, he confesses in the
second edition to “a lack of that self-confidence” which would have enabled him to reform
the Galenic teachings about the heart and blood…
Vesalius says in De Fabrica that the septum is “formed from the very densest substance
of the heart,” and that—although the septum “abounds on both sides with pits”—“of
these pits none, so far as the senses can perceive, penetrate from the right to the left
ventricle.” And this leads him only to conclude: “We are thus forced to wonder at the art
of the Creator by which the blood passes from the right to the left ventricle through pores
which elude the sight.” In the second edition of De Fabrica, [Basel, 1555] this passage
was somewhat rewritten:
Although sometimes these pits are conspicuous, yet none, so far as the senses can perceive,
passes from the right to the left ventricle… I have not come across even the most hidden
channels by which the septum of the ventricles is pierced. Yet such channels are described
by teachers of anatomy who have absolutely decided that blood is taken from the right to the
left ventricle. I, however, am in great doubt as to the office of the heart in this part.
In yet another discussion of this subject, he indicated his gradual independence from
Galen:
In considering the structure of the heart and the use of its parts, I have brought my words
for the most part into agreement with the teachings of Galen: not because I thought that
these were on every point in harmony with the truth, but because, in referring now and again
to a new use and purpose for the parts, I still distrust myself. Not long ago I would not have
dared to turn aside, even a nail’s breadth from the opinion of Galen, the prince of
physicians… But the septum of the heart is as thick, dense, and compact as the rest of the
heart. I do not, therefore, know… in what way even the smallest particle can be transferred
from the right to the left ventricle through the substance of that septum…
Vesalius could not easily [cast doubts on Galenic physiology, particularly the heart’s action]
since he would thereby “upset the whole of the current notions of the workings of the human
body without putting anything in its place”; and this “Vesalius hesitated to do.”… Vesalius
was not a full-fledged revolutionary. He did not simply and straightforwardly deny the
possibility that the human body could function as Galen had taught and as Vesalius’s
contemporaries still believed….
[In] De Fabrica, Vesalius did not adopt the bold stance of revolt that he had adopted in
Padua and in Bologna in his public use of articulated skeletons of man and ape to show that
Galen’s anatomy of the bones was valid for the animals he had dissected and not for man.
Vesalius’s non-revolutionary attitude, even with respect to his correcting some of
Galen’s errors, was no doubt related to his personality. But we must also keep in mind that
1543 was a little early for a full expression of the revolutionary attitude in the sciences that
we find in the writings of Galileo, Descartes, and Harvey and later scientists of the
seventeenth century. Furthermore, Vesalius was steeped in the humanist tradition,
which was founded on a belief in the greatness of classical philosophy, letters, art, and
science and which sought to restore the values of antique culture. Vesalius probably
saw his role as an improver of Greek anatomy and a restorer of the Greek tradition
of dissection and not therefore as the author of a revolutionary and frontal attack on
the current versions of Galenic science. [176-183]
QUESTIONS:
1) Why does the author argue that Vesalius was a reformer, but not a revolutionary?
Explain.
2) What are the alleged pores in the septum and what were Vesalius’s views regarding
them?
3) Why is De Fabrica (1543) considered a significant historical work? Elaborate. [This
may require consulting the Additional Resources]