Cusanus And The First Suggestion Of Laboratory Methods In Medicine
As illustrating how, as we know more about the details of medical
history, the beginnings of medical science and medical practice are
pushed back farther and farther, a discussion in the Berliner klinische
Wochenschrift a dozen years ago is of interest. Professor Ernest von
Leyden, in sketching the history of the taking of the pulse as an
important aid in diagnostics, said that John Floyer was usually referred
to as th
man who introduced the practice of determining the pulse rate
by means of the watch. His work was done about the beginning of the
eighteenth century. Professor von Leyden suggested, however, that
William Harvey, the English physiologist, to whom is usually attributed
the discovery of the circulation of the blood, had emphasized the value
of the pulse in medical diagnosis, and also suggested the use of the
watch in counting the pulse. Professor Carl Binz, of the University of
Bonn, commenting on these remarks of Professor von Leyden, called
attention to the fact that more than a century before the birth of
either of these men, even the earlier, to whom the careful measurement
of the pulse rate is thus attributed as a discovery, a distinguished
German churchman, who died shortly after the middle of the fifteenth
century, had suggested a method of accurate estimation of the pulse
that deserves a place in medical history.
This suggestion is so much in accord with modern demands for greater
accuracy in diagnosis that it seems not inappropriate to talk of it as
the first definite attempt at laboratory methods in the department of
medicine. The maker of the suggestion, curiously enough, was not a
practising physician, but a mathematician and scholar, Cardinal Nicholas
of Cusa, who is known in history as Cusanus from the Latin name of the
town Cues on the Moselle River, some twenty-five miles south of Treves,
where he was born. His family name, Nicholas Krebs, has been entirely
lost sight of in the name derived from his native town, which is the
only reason why most of the world knows anything about that town.
Cardinal Cusanus suggested that in various forms of disease and at
various times of life, as in childhood, boyhood, manhood, and old age,
the pulse was very different. It would be extremely valuable to have
some method of accurately estimating, measuring, and recording these
differences for medical purposes. At that time watches had not yet been
invented, and it would have been very difficult to have estimated the
time by the clocks, for almost the only clocks in existence were those
in the towers of the cathedrals and of the public buildings. The first
watches, Nuremberg eggs, as they were called, were not made by Peter
Henlein until well on into the next century. The only method of
measuring time with any accuracy in private houses was the clepsydra or
water-clock, which measured the time intervals by the flow of a
definite amount of water. Cardinal Cusanus suggested then that the
water-clock should be employed for estimating the pulse frequency. His
idea was that the amount of water which flowed while a hundred beats of
the pulse were counted, should be weighed, and this weight compared with
that of the average weight of water which flowed while a hundred beats
of the normal pulse of a number of individuals of the same age and
constitution were being counted.
This was a very single and a very ingenious suggestion. We have no means
of knowing now whether it was adopted to any extent or not. It may seem
rather surprising that a cardinal should have been the one to make such
a suggestion. Cusanus, however, was very much interested in mathematics
and in the natural sciences, and we have many wonderful suggestions from
his pen. He was the first, for instance, to suggest, more than a century
before Copernicus, that the earth was not the centre of the universe,
and that it would not be absolutely at rest or, as he said, devoid of
all motion. His words are: Terra igitur, quae centrum esse nequit, motu
omni carere non potest. He described very clearly how the earth moved
round its own axis, and then he added, what cannot fail to be a
surprising declaration for those in the modern times who think such an
idea of much later origin, that he considered that the earth itself
cannot be fixed, but moves as do the other stars in the heavens. The
expression is so astonishing at that time in the world's history that it
seems worth the while to give it in its original form, so that it may be
seen clearly that it is not any subsequent far-fetched interpretation
of his opinion, but the actual words themselves, that convey this idea.
He said: Consideravi quod terra ista non potest esse fixa, sed movetur
ut aliae stellae.
How clearly Cusanus anticipated another phase of our modern views may be
judged from what he has to say in De Docta Ignorantia with regard to
the constitution of the sun. It is all the more surprising that he
should by some form of intuition reach such a conclusion, for the
ordinary sources of information with regard to the sun would not suggest
such an expression except to a genius, whose intuition outran by far the
knowledge of his time. The Cardinal said: To a spectator on the surface
of the sun the splendor which appears to us would be invisible, since it
contains, as it were, an earth for its central mass, with a
circumferential envelope of light and heat, and between the two an
atmosphere of water and clouds and of ambient air. After reading that
bit of precious astronomical science announced nearly five centuries
ago, it is easy to understand how Copernicus could have anticipated
other phases of our knowledge, as he did in his declarations that the
figure of the earth is not a sphere, but is somewhat irregular, and that
the orbit of the earth is not circular.
Cusanus was an extremely practical man, and was constantly looking for
and devising methods of applying practical principles of science to
ordinary life. As we shall see in discussing his suggestion for the
estimation of the pulse rate later on, he made many other similar
suggestions for diagnostic purposes in medicine, and set forth other
applications of mathematics and mechanics to his generation.
Many of Cusanus' books have curiously modern names. He wrote, for
instance, a series of mathematical treatises, in Latin of course, on
Geometric Transmutations, on Arithmetical Complements, on
Mathematical Complements, on Mathematical Perfection, and on The
Correction of the Calendar. In his time the calendar was in error by
more than nine days, and Cusanus was one of those who aroused sufficient
interest in the subject, so that in the next century the correction was
actually made by the great Jesuit mathematician, Father Clavius. Perhaps
the work of Cusanus that is best known is that On Learned Ignorance--De
Docta Ignorantia, in which the Cardinal points out how many things that
educated people think they know are entirely wrong. It reminds one very
much of Josh Billings's remark that it is not so much the ignorance of
mankind that makes them ridiculous, as the knowing so many things that
ain't so. It is from this work that the astronomical quotations which we
have made are taken. The book that is of special interest to physicians
is his dialogue On Static Experiments, which he wrote in 1450, and
which contains the following passages:
Since the weight of the blood and the urine of a healthy and
of a diseased man, of a young man and an old man, of a German
and an African, is different for each individual, why would it
not be a great benefit to the physician to have all of these
various differences classified? For I think that a physician
would make a truer judgment from the weight of the urine
viewed in connection with its color than he could make from
its color alone, which might be fallacious. So, also, weight
might be used as a means of identifying the roots, the stems,
the leaves, the fruits, the seeds, and the juice of plants if
the various weights of all the plants were properly noted,
together with their variety, according to locality. In this
way the physician would appreciate their nature better by
means of their weight than if he judged them by their taste
alone. He might know, then, from a comparison of the weights
of the plants and their various parts when compared with the
weight of the blood and the urine, how to make an application
and a dosage of drugs from the concordances and differences of
the medicaments, and even might be able to make an excellent
prognosis in the same way. Thus, from static experiments, he
would approach by a more precise knowledge to every kind of
information.
Do you not think if you would permit the water from the
narrow opening of a clepsydra [water-clock] to flow into a
basin for as long as was necessary to count the pulse a
hundred times in a healthy young man, and then do the same
thing for an ailing young man, that there would be a
noticeable difference between the weights of the water that
would flow during the period? From the weight of the water,
therefore, one would arrive at a better knowledge of the
differences in the pulse of the young and the old, the healthy
and the unhealthy, and so, also, as to information with regard
to various diseases, since there would be one weight and,
therefore, one pulse in one disease, and another weight and
another pulse in another disease. In this way a better
judgment of the differences in the pulse could be obtained
than from the touch of the vein, just as more can be known
from the urine about its weight than from its color alone.
Just in the same way would it not be possible to make a more
accurate judgment with regard to the breathing, if the
inspirations and expirations were studied according to the
weight of the water that passed during a certain interval? If,
while water was flowing from a clepsydra, one were to count a
hundred expirations in a boy, and then in an old man, of
course, there would not be the same amount of water at the end
of the enumeration. Then this same thing might be done for
other ages and states of the body. As a consequence, when the
physician once knew what the weight of water that represented
the number of expirations of a healthy boy or youth, and then
of an individual of the same age ill of some infirmity or
other, there is no doubt that, by this observation, he will
come to a knowledge of the health or illness and something
about the case, and, perhaps, also with more certainty would
be able to choose the remedy and the dose required. If he
found in a healthy young man apparently the same weight as in
an old and decrepit individual, he might readily be brought to
the conclusion that the young man would surely die, and in
this way have some evidence for his prognosis in the case.
Besides, if in fevers, in the same way, careful studies were
made of the differences in the weight of water for pulse and
respiration in the warm and the cold paroxysms, would it not
be possible thus to know the disease better and, perhaps, also
get a more efficacious remedy?
As will be seen from this passage, Cusanus had many more ideas than
merely the accurate estimation of the pulse frequency when he suggested
the use of the water-clock. Evidently the thought had come to him that
the specific gravity of the substances, that is, their weight in
comparison to the weight of water, might be valuable information.
Before his time, physicians had depended only on the color and the taste
of the urine for diagnostic purposes. He proposed that they should weigh
it, and even suggested that they should weigh, also, the blood, I
suppose in case of venesection, for comparison's sake. He also thought
that the comparative weight of various roots, stems, leaves, juices of
plants might give hints for the therapeutic uses of these substances.
This is the sort of idea that we are apt to think of as typically
modern. Specific gravities and atomic weights have been more than once
supposed to represent laws in therapeutics, which so far, however, we
have not succeeded in finding, but it is interesting to realize that it
is nearly five hundred years since the first thought in this line was
clearly expressed by a distinguished thinker and scientific writer.
There are many interesting expressions in Cusanus' writings which
contradict most of the impressions commonly entertained with regard to
the scholars of the Middle Ages. It is usually assumed that they did not
think seriously, but speculatively, that they feared to think for
themselves, neglected the study of nature around them, considered
authority the important source of knowledge, and were as far as possible
from the standpoint of modern scientific students and investigators.
Here is a passage from Nicholas, on knowing and thinking, that might
well have been written by a great intellectual man at any time in the
world's history, and that could only emanate from a profound scholar at
any time.
To know and to think, to see the truth with the eye of the
mind, is always a joy. The older a man grows the greater is
the pleasure which it affords him, and the more he devotes
himself to the search after truth, the stronger grows his
desire of possessing it. As love is the life of the heart, so
is the endeavor after knowledge and truth the life of the
mind. In the midst of the movements of time, of the daily work
of life, of its perplexities and contradictions, we should
lift our gaze fearlessly to the clear vault of heaven, and
seek ever to obtain a firmer grasp of and a keener insight
into the origin of all goodness and beauty, the capacities of
our own hearts and minds, the intellectual fruits of mankind
throughout the centuries, and the wondrous works of nature
around us; at the same time remembering always that in
humility alone lies true greatness, and that knowledge and
wisdom are alone profitable in so far as our lives are
governed by them.
The career of Nicholas of Cusa is interesting, because it sums up so
many movements, and, above all, educational currents in the fifteenth
century. He was born in the first year of the century, and lived to be
sixty-four. He was the son of a wine grower, and attracted the attention
of his teachers because of his intellectual qualities. In spite of
comparatively straitened circumstances, then, he was afforded the best
opportunities of the time for education. He went first to the school of
the Brethren of the Common Life at Deventer, the intellectual cradle of
so many of the scholars of this century. Such men as Erasmus, Conrad
Mutianus, Johann Sintheim, Hermann von dem Busche, whom Strauss calls
the missionary of human wisdom, and the teacher of most of these,
Alexander Hegius, who has been termed the schoolmaster of Germany, with
Nicholas of Cusa and Rudolph Agricola and others, who might readily be
mentioned, are the fruits of the teaching of these schools of the
Brethren of the Common Life, in one of which Thomas a Kempis, the author
of The Imitation of Christ, was, for seventy years out of his long
life of ninety, a teacher.
Cusanus succeeded so well at school that he was later sent to the
University of Heidelberg, and subsequently to Padua, where he took up
the study of Roman law, receiving his doctorate at the age of
twenty-three. This series of educational opportunities will be
surprising only to those who do not know educational realities at the
beginning of the fifteenth century. There has never been a time when a
serious seeker after knowledge could find more inspiration. On his
return to Germany, Father Krebs became canon of the cathedral in
Coblenz. This gave him a modest income, and leisure for intellectual
work which was eagerly employed. He was scarcely more than thirty when
he was chosen as a delegate to the Council at Basel. After this he was
made Archdeacon of the Cathedral of Luettich, and from this time his rise
in ecclesiastical preferment was rapid. He had attracted so much
attention at the Council of Basel that he was chosen as a legate of the
Pope for the bringing about certain reforms in Germany. Subsequently he
was sent on ecclesiastical missions to the Netherlands, and even to
Constantinople. At the early age of forty he was made a Cardinal. After
this he was always considered as one of the most important consultors
of the Papacy in all matters relating to Germany. During the last
twenty-five years of his life in all the relations of the Holy See to
Germany, appeal was constantly made to the wisdom, the experience, and
the thoroughly conservative, yet foreseeing, judgment of this son of the
people, whose education had lifted him up to be one of the leaders of
men in Europe.
It was during this time that he wrote most of his books on mathematics,
which have earned for him a prominent place in Cantor's History of
Mathematics, about a score of pages being devoted to his work. Much of
his thinking was done while riding on horseback or in the rude vehicles
of the day on the missions to which he was sent as Papal Legate. He is
said to have worked out the formula for the cycloid curve while watching
the path described by flies that had lighted on the wheels of his
carriage, and were carried forward and around by them. His scientific
books, though they included such startling anticipations of Copernicus'
doctrines as we have already quoted (Copernicus did not publish the
first sketch of his theory for more than a quarter of a century after
Cusanus' death), far from disturbing his ecclesiastical advancement or
injuring his career as a churchman, seem actually to have been
considered as additional reasons for considering him worthy of
confidence and consultation.
As the result of his careful studies of conditions in Germany, he
realized very clearly how much of unfortunate influence the political
status of the German people, with their many petty rulers and the
hampering of development consequent upon the trivial rivalries, the
constant bickerings, and the inordinate jealousies of these numerous
princelings, had upon his native country. Accordingly, towards the end
of his life he sketched what he thought would be the ideal political
status for the German people. As in everything that he wrote, he went
straight to the heart of the matter and, without mincing words, stated
just exactly what he thought ought to be done. Considering that this
scheme of Cusanus for the prosperity and right government of the German
people was not accomplished until more than four centuries after his
death, it is interesting, indeed, to realize how this clergyman of the
middle of the fifteenth century should have come to any such thought.
Nothing, however, makes it clearer than this, that it is not time that
fosters thinking, but that great men at any time come to great thoughts.
Cusanus wrote:
The law and the kingdom should be placed under the protection
of a single ruler or authority. The small separate governments
of princes and counts consume a disproportionately large
amount of revenue without furnishing any real security. For
this reason we must have a single government, and for its
support we must have a definite amount of the income from
taxes and revenues yearly set aside by a representative
parliament and before this parliament (reichstag) must be
given every year a definite account of the money that was
spent during the preceding year.
Cusanus' life and work stand, then, as a type of the accomplishment, the
opportunities, the power of thought, the practical scholarship, the
mathematical accuracy, the fine scientific foresight of a scholar of
the fifteenth century. For us, in medicine, it is interesting indeed to
realize that it is from a man of this kind that a great new departure in
medicine with regard to the employment of exact methods of diagnosis had
its first suggestion in modern times. The origin of that suggestion is
typical. It has practically always been true that it was not the man who
had exhausted, or thought that he had done so, all previous medical
knowledge, who made advances in medicine for us. It has nearly always
been a young man early in his career, and at a time when, as yet, his
mind was not overloaded with the medical theories of his own time.
Cusanus was probably not more than thirty when he made the suggestion
which represents the first practical hint for the use of laboratory
methods in modern medicine. It came out of his thoughtful consideration
of medical problems rather than from a store of garnered information as
to what others thought. It is a lesson in the precious value of breadth
of education and serious training of mind for real progress at all
times.