well as your fortunate discoveries, are highly praised by the
learned of your country. The fatherland congratulates itself upon
such a citizen, I upon such a pupil, through whose efforts anatomy
makes daily progress, and our lympathic vessels are traced out more
and more. You divide honors with Wharton, since you have added to
his internal duct an external one, and have thereby discovered the
sources of the saliva concerning which many have hitherto dreamed
much, but which no one has (permit the expression) pointed out with
the finger. Continue, my Steno, to follow the path to immortal glory
which true anatomy holds out to you.
Under the stimulus of such encouragement, it is no wonder that Stensen
continued his original work with eminent success. He published an
extensive article on the glands of the eye and the vessels of the
nose.
Bartholini wrote to him again: "Your fame is growing from day to day,
for your pen and your sharp eye know no rest." Later he wrote {145}
again: "You may count upon the favor of the king as well as upon the
applause of the learned." After three years at the University of
Amsterdam, Steno returned to Copenhagen, where he published his
"Anatomical Observations Concerning the Muscles and Glands." It was in
this book that he announced his persuasion that the heart was a
muscle. As he said himself, "the heart has been considered the seat of
natural warmth, the throne of the soul; but if you examine it more
closely, it turns out to be nothing but a muscle. The men of the past
would not have been so grossly mistaken with regard to it, had they
not preferred their imaginary theories to the results of the simple
observation of nature." It is easy to understand that this observation
created a very great sensation. It had much to do with overthrowing
certain theoretic systems of medicine, and nearly a century later the
distinguished physiologist, Haller, did not hesitate to proclaim the
volume in which it occurs, as a "golden book."
Stensen's studies in anatomy stamp him as an original genius of a high
order, and this is all the more remarkable because his career occurs
just in those years when there were distinguished discoverers in
anatomy in every country in Europe. When Stensen began his work in
anatomy, Harvey was still alive. The elder Bartholini, the first who
ever established an anatomical museum, was another of his
contemporaries. Among the names of distinguished anatomists {146} with
whom Stensen was brought intimately in contact during the course of
his studies in Holland, France and Italy are those of Swammerdam, Van
Horne, and Malpighi. There is no doubt that his intercourse with such
men sharpened his own intellectual activity, and increased his
enthusiasm for original investigation in contradistinction to the mere
accumulation of information.
His contemporaries, indeed, exhausted most of the adjectives of the
Latin language in trying to express their appreciation of his acuity
of observation. He was spoken of as _oculatissimus_--that is, as
being all eyes, _subtilissimus, acutissimus, sagacissimus_ in his
knowledge of the human body, and as the most perspicacious anatomist
of the time. Leibnitz and Haller were in accord in considering him one
of the greatest of anatomists. In later years this admiration for
Stensen's genius has not been less enthusiastically expressed. Haeser,
in his "History of Medicine," the third edition of which appeared at
Jena in 1879, says: "Among the greatest anatomists of the seventeenth
century belongs Nicholas Steno, the most distinguished pupil of Thomas
Bartholini. Steno was rightly considered in his own time as one of the
greatest of anatomical discoverers. There is scarcely any part of the
human body the knowledge of which was not rendered more complete by
his investigations."
The most valuable discovery made by Stensen was undoubtedly that the
heart is a muscle. It {147} must not be forgotten that in his time,
Harvey's discovery of the circulation of the blood was not yet
generally accepted; indeed, there were many who considered the theory
(as they called it) of the English investigator as one of the passing
fads of medicine. Two significant discoveries, made after Harvey,
served, however, to establish the theory of the circulation of the
blood on a firm basis and to make it a definite medical doctrine. The
most important of these was Malpighi's discovery that the
capillaries--that is, the minute vessels at the end of the arterial
tree on the surface of the body and in various organs--served as the
direct connexion between the veins and the arteries. This demonstrated
just how the blood passed from the arterial to the venous system.
Scarcely less important, however, for the confirmation of Harvey's
teaching was Stensen's demonstration of the muscular character of the
tissue of the heart.
Some of his observations upon muscles are extremely interesting, and,
though he made many mistakes in explaining their function, he added
not a little to the anatomical and physiological knowledge of the time
in their regard. He seems to have been one of the first to recognize
the fact that in the higher animals the heart may continue to beat for
a considerable time after the animal is apparently dead; and, indeed,
that by irritation of the removed heart, voluntary contractions may be
brought about which will continue spontaneously for some moments.
{148}
With regard to the objections made by some, that such studies as these
upon muscles could scarcely be expected to produce any direct result
for the treatment of disease, or in the ordinary practice of medicine,
Stensen said in reply that it is only on the basis of the anatomical,
physiological, and pathological observation that progress in medicine
is to be looked for. In spite, then, of the discouragement of the
many, who look always for immediate practical results, Stensen
continued his investigation, and even proposed to make an extended
study of the mechanism of the muscular action.
In the meantime, however, there had gradually been coming into his
life another element which was to prove more absorbing than even his
zeal for scientific discovery. It is this which constitutes the
essential index of the man's character and has been sadly
misunderstood by many of his biographers.
Sir Michael Foster, of Cambridge, England, in his "Lectures on the
History of Physiology," originally delivered as the Lane Lectures at
Cooper Medical College, San Francisco, said:--
While thus engaged, still working at physiology, Stensen turned his
versatile mind to other problems, as well as to those of comparative
anatomy, and especially to those of the infant, indeed hardly as yet
born, science of geology. His work "De solido intra solidum" is
thought by geologists to be a brilliant effort toward the beginning
of their science
In 1672 he returned for a while to his native city of {149}
Copenhagen, but within two years he was back again at Florence; and
then there came to him, while as yet a young man of some thirty-six
summers, a sudden and profound change in his life.
In his early days he had heard much, too much perhaps, of the
doctrines of Luther. Probably he had been repelled by the austere
devotion which ruled the paternal roof. And, as his answer to
Bossuet shows, his university life and studies, his intercourse with
the active intellects of many lands, and his passion for inquiry
into natural knowledge, had freed him from passive obedience to
dogma. He doubtless, as did many others of his time, looked upon
himself as one of the enlightened, as one raised above the barren
theological questions which were moving the minds of lesser men
Yet it was out of this sceptical state of mind, that life in Italy and
intimate contact with ecclesiastics and religious, so often said to be
likely not to have any such effect, brought this acute scientific mind
into the Catholic Church. Nor did he become merely a formal adherent,
but an ardent believer, and then an enthusiastic proselytizer. One
American writer of a history of medicine, in his utter failure to
comprehend or sympathize with the change that came over Stensen,
speaks of him as having become at the end of his life a mere
"peripatetic converter of heretics." This phase of Stensen's life has,
however, as ample significance as any that preceded it.
Steno's expectations of the professorship of anatomy at Copenhagen
were disappointed, but the appointment went to Jacobson, whose work
indeed is scarcely less distinguished than that of {150} his
unsuccessful rival. The next few years Stensen passed in Paris, where
he was assiduous in making dissections, and where he attracted much
attention; and then, somewhat later, in Italy; in 1665 and 1666 he was
in Rome. Thence he went to Florence, in order to perfect himself in
Italian. The next few years he spent in this city, having received the
appointment of body physician to the Grand Duke, as well as an
appointment of visiting physician, as we would call it now, to the
Hospital of Santa Maria Nuova.
It was while at Florence that the whole current of Stensen's life was
changed by his conversion to Catholicity. His position as physician to
the Hospital of Santa Maria Nuova brought him frequently into the
apothecary shop attached to the hospital. As a result he came to know
very well the religious in charge of the department, Sister Maria
Flavia, the daughter of a well-known Tuscan family. At this time she
had been for some thirty-five years a nun. Before long she learned
that the distinguished young physician, at this time scarcely thirty
years of age, who was such a pleasant gentleman in all his ways, was a
Lutheran. She began, as she told afterwards, first by prayer, and then
by friendly suggestions, to attempt to win him to the Catholic Church.
Stensen, who seems already to have been well-disposed toward the
Church, and who had always been known for a wonderful purity of heart
and simplicity of character, listened very willingly to the naive
words of the {151} old religious, who might very well have been his
mother.
Many years later, by the command of her confessor, the good Sister
related the detailed story of his conversion. She began very simply by
telling him one day that if he did not accept the true Catholic faith,
he would surely go to hell. He listened to this without any
impatience, and she said it a number of other times, half jokingly
perhaps, but much more than half in earnest. As he listened so kindly,
she said to him one day that he must pray every day to God to let him
know the truth. This he promised to do and, as she found out from his
servant (what is it these nuns do not find out?) he did pray every
evening. One day, while he was in the apothecary shop, the Angelus
bell rang, and she asked him to say the Angelus. He was perfectly
willing to say the first part of the Hail Mary, but he did not want to
say the second part, as he did not believe in the invocation of the
Blessed Virgin and the saints. Then she asked him to visit the Church
of the Blessed Virgin, the Santissima Nunziata, which he did. After
this she suggested to him that he should abstain from meat on Fridays
and Saturdays, which he promised to do, and which the good nun found
out once more from his servant, he actually did do. And then the
religious thought it was time to suggest that he should consult a
clergyman, and his conversion was not long delayed.
Young Stensen seems to have been the object {152} of solicitude on the
part of a number of the good, elderly women with whom he was brought
in contact. He discussed with Signora Arnolfini the great difficulty
he had in believing the mystery of the Eucharist. Another good woman,
the Signora Lavinia Felice, seeing how interested he was in things
Catholic, succeeded in bringing him to the notice of a prominent
Jesuit in Florence. As his friend, Sister Maria Flavia, had
recommended the same Father to him, he followed the advice all the
more readily, and it was not long before his last doubts were solved.
It was after his conversion that Stensen received his invitation to
become the professor of anatomy at the University of Copenhagen. Much
as he had become attached to Florence, the thought of returning to his
native city was sweet; and then besides he hoped that he might be able
to influence his countrymen in their views toward the Catholic Church.
It was not long, however, before the bigotry of his compatriots made
life so unpleasant for him in Copenhagen that he resigned his position
and returned to Italy. Various official posts in Florence were open
for him, but now he had resolved to devote himself to the service of
the Church, and so he became a priest. His contemporary, the Cardinal
Archbishop of Florence, said with regard to him: "Already as a member
of a Protestant sect he had lived a life of innocence and had
practised all the moral virtues. After his conversion he had marked
out for himself so severe a method of life and had {153} remained so
true to it that in a very short time he reached a high degree of
perfection." The Archbishop does not hesitate to say that he had
become a man of constant union with God and entirely dead to himself.
There was very little hesitation, then, in accepting him as a
candidate for the priesthood, and as his knowledge of theology was
very thorough, most of the delay in raising him to that dignity came
from his own humility and his desire to prepare himself properly for
the privilege. He made the exercises of St. Ignatius as part of his
preparation, and after his ordination it was a source of remark with
how much devotion he said his first and all succeeding Masses. It was
not long before the piety of Stensen's life attracted great attention.
At this time he was in frequent communication with such men as Spinoza
and Leibnitz, the distinguished philosophers. It is curious to think
of the ardent mystic, the pantheistic philosopher, and the speculative
scientist, so different in character, having many interests in common.
It was during these years in Italy that Stensen did what must be
considered, undoubtedly, his most important work, even more important,
if possible, than his anatomical discoveries. This was his foundation
of the science of geology. As has been well said in a prominent
text-book of geology, his book on this subject sets him in that group
of men who as prophets of science often run far ahead of their times
to point out the path which later centuries will follow in the road of
{154} knowledge. It is rather surprising to find that the seventeenth
century must enjoy the privilege of being considered the cradle of
geological knowledge. There is no doubt, however, that the great
principles of the science were laid down in Stensen's little book,
which he intended only to be an introduction to a more extensive work,
but the latter was unfortunately never completed, nor, indeed, so far
as we are able to decide now, ever seriously begun.
One of the basic principles of the science of geology Stensen taught
as follows: "If a given body of definite form, produced according to
the laws of nature, be carefully examined, it will show in itself the
place and manner of its origin." This principle he showed would apply
so comprehensively that the existence of many things, hitherto
apparently inexplicable, became rather easy of solution. It must not
be forgotten that before this time two explanations for the existence
of peculiar bodies, or of ordinary bodies, in peculiar places, had
been offered. According to one school of thought, the fossils found
deep in the earth, or sometimes in the midst of rocks, had been
created there. It was as if the creative force had run beyond the
ordinary bounds of nature and had produced certain things, ordinarily
associated with life, even in the midst of dead matter. The other
explanation suggested was that the flood had in its work of
destruction upon earth caused many anomalous displacements of living
things, and had buried some of the {155} animals under such
circumstances that later they were found even beneath rocks, or deep
down in the earth, far beyond where the animals could be supposed to
have penetrated by any ordinary means during life.
Stensen had observed very faithfully the various strata that are to be
found wherever special appearances of the earth's surface were
exposed, or wherever deep excavations were made. His explanation of
how these various strata are formed will serve to show, perhaps better
than anything else, how far advanced he was in his realization of
ideas that are supposed to belong only to modern geology. He said:
"The powdery layers of the earth's surface must necessarily at some
time have been held in suspension in water, from which they were
precipitated by their own weight. The movement of the fluid scattered
the precipitate here and there and gave to it a level surface."
"Bodies of considerable circumference," Stensen continues, "which are
found in the various layers of the earth, followed the laws of gravity
as regards their position and their relations to one another. The
powdery material of the earth's strata took on so completely the form
of the bodies which it surrounded that even the smallest apertures
became filled up and the powdery layer fitted accurately to the
surface of the object and even took something of its polish."
With regard to the composition of the various strata of the earth, the
father of geology {156} considered that if in a layer of rock all the
portions are of the same kind there is no reason to deny that such a
layer came into existence at the time of creation, when the whole
surface of the earth was covered with fluid. If, however, in any one
stratum portions of another stratum are found, or if the remains of
plants or animals occur, there is no doubt that such a stratum had not
its origin at the time of creation, but came into existence later.
If there is to be found in a stratum traces of sea salt, or the
remains of sea animals, or portions of vessels, or such like objects,
which are only to be encountered at the bottom of the sea, then it
must be considered that this portion of the earth's surface once was
below the sea level, though it may happen that this occurred only by
the accident of a flood of some kind. The great distance from the sea,
or other body of water, at the present time, may be due to the sinking
of the water level in the neighborhood, or by the rising up of a
mountain from some internal terrestrial cause in the interval of time.
He continues:--
If one finds in any layer remains of branches of trees, or herbs,
then it is only right to conclude that these objects were brought
together because of flood or of some such condition in the place
where they are now found. If in a layer coal and ashes and burnt
clay or other scorched bodies are found, then it seems sure that
some place in the neighborhood of a watercourse a fire took place,
and this is all the more sure when the whole layer consists of ashes
and {157} coal. Whenever in the same place the material of which all
the layers is composed is the same, there seems to be no doubt that
the fluid to which the stratum owes its origin did not at different
times obtain different material for its building purposes.
In respect to the mountains and their formation, Stensen said very
definitely:--
All the mountains which we see now have not existed from the
beginning of things. Mountains do not, however, grow as do plants.
The stones of which mountains are composed have only a certain
analogy with the bones of animals, but have no similarity in
structure or in origin, nor have they the same function and purpose.
Mountain ranges, or chains of mountains as some prefer to call them,
do not always run in certain directions, though this has sometimes
been claimed. Such claims correspond neither to reason nor to
observation. Mountains may be very much disturbed in the course of
years. Mountain peaks rise and fall somewhat. Chasms open and shut
here and there in them, and though there are those who pretend that
it is only the credulous who will accept the stories of such
happenings, there is no doubt that they have been established on
trustworthy evidence.
In the course of his observations in Italy, Stensen had seen many
mussel shells, which had been gathered from various layers of the
earth's surface. With regard to the shells themselves, he said that
there could be no doubt that they had come as the excretion of the
mantle of the mussel, and that the differences that could be noted in
them were in accordance with the varying forms of these animals. He
pointed out, however, that some of the mussel shells found in {158}
strata of rock were really mussel shells in every respect as regards
the material of which they were composed as well as their interior
structure and their external form, so that there could be no possible
question of their origin. On the other hand, a certain number of the
so-called mussel shells were not composed of the ordinary materials of
which such shells are usually made up; but had indeed only the
external form of genuine shells. Stensen considered, however, that
even these must be regarded as originating in real mussel shells, the
original substance having been later on replaced by other material. He
explained this replacement process in very much the same way that we
now suggest the explanation of various processes of petrification.
There is no doubt that in this he went far beyond his contemporaries,
and pointed out very clearly what was to be the teaching of
generations long after his own.
The same principles he applied to mussel shells, Stensen considered
must have their application also to all other portions of animal
bodies, teeth, bones, whole skeletons, and even more perishable animal
materials that might be found buried in the earth's strata. His
treatment of the question of the remains of plants was quite as
satisfactory as that of the animals. He distinguished between the
impressions of plants, the petrification of plants, the carbonization
of plants, and then dwelt somewhat on the tendency of certain minerals
to form dendrites, that is, branching {159} processes which look not
unlike plants. He pointed out how easy it is to be deceived by these
appearances, and stated very clearly the distinction between real
plants and such simulated ones.
It will be scarcely necessary for us to apologize for having given so
much space to Stensen's work on geology. Many distinguished
scientists, however, have insisted that no greater advance at the
birth of a science was ever made than that which Stensen accomplished
in his geological work. Hoffman says that after carefully studying the
work, he has come to the conclusion that of the successors of Stensen,
no student of the mountains down to Werner's day had succeeded in
comprehending so many fruitful points of view in geology. None of his
great successors in geology has succeeded in introducing so many new
ideas into the science as the first great observer. For several
centuries most of his successors in geology remained far behind him in
creative genius, and so there is little progress worth while noting in
the knowledge of the method of earth formation, until almost the
beginning of the nineteenth century, though his little book was
written in 1668 and 1669.