Dioscorides as medical botanist is discussed by Charles Singer in an
article ‘Greek Biology and the Rise of Modern Biology’; _Studies in the
History and Method of Science_, vol. ii, Oxford, 1921.
[88] This manuscript is at the University Library at Leyden, where it
is numbered Voss Q 9.
[Illustration: Fifth century drawings from JULIANA ANICIA MS., copied
from originals of first century B. C.(?)
Fig. 9.
ΣΟΝΚΟΣ ΤΡΥΦΕΡΟΣ = _Crepis paludosa_, _Mœn._]
[Illustration: Fig. 10.
ΓΕΡΑΝΙΟΝ = _Erodium malachoides_, _L._]
But the greatest biologist of the late Greek period, and indeed one of
the greatest biologists of all time, was Claudius Galen of Pergamon
(A. D. 131-201). Galen devoted himself to medicine from an early
age, and in his twenty-first year we hear of him studying anatomy at
Smyrna under Pelops. With the object of extending his knowledge of
drugs he early made long journeys to Asia Minor. Later he proceeded to
Alexandria, where he improved his anatomical equipment, and here, he
tells us, he examined a human skeleton. It is indeed probable that his
direct practical acquaintance with human anatomy was limited to the
skeleton and that dissection of the human body was no longer carried
on at Alexandria in his time. Thus his physiology and anatomy had to
be derived mainly from animal sources. He is the most voluminous of
all ancient scientific writers and one of the most voluminous writers
of antiquity in any department. We are not here concerned with the
medical material which mainly fills these huge volumes, but merely with
the physiological views which not only prevailed in medicine until
Harvey and after, but also governed for fifteen hundred years alike
the scientific and the popular ideas on the nature and workings of the
animal body, and have for centuries been embedded in our speech. A
knowledge of these physiological views of Galen is necessary for any
understanding of the history of biology and illuminates many literary
allusions of the Middle Ages and Renaissance.
Between the foundation of the Alexandrian school and the time of Galen,
medicine was divided among a great number of sects. Galen was an
eclectic and took portions of his teaching from many of these schools,
but he was also a naturalist of great ability and industry, and knew
well the value of the experimental way. Yet he was a somewhat windy
philosopher and, priding himself on his philosophic powers, did not
hesitate to draw conclusions from evidence which was by no means always
adequate. The physiological system that he thus succeeded in building
up we may now briefly consider (fig. 11).
The basic principle of life, in the Galenic physiology, is a _spirit_,
_anima_ or _pneuma_, drawn from the general world-soul in the act of
respiration. It enters the body through the _rough artery_ (τραχεῖα
ἀρτηρία, _arteria aspera_ of mediaeval notation), the organ known to
our nomenclature as the trachea. From this trachea the pneuma passes to
the lung and then, through the _vein-like artery_ (ἀρτηρία φλεβώδης,
_arteria venalis_ of mediaeval writers, the pulmonary vein of our
nomenclature), to the left ventricle. Here it will be best to leave it
for a moment and trace the vascular system along a different route.
Ingested food, passing down the alimentary tract, was absorbed as chyle
from the intestine, collected by the portal vessel, and conveyed by it
to the liver. That organ, the site of the innate heat in Galen’s view,
had the power of elaborating the chyle into venous blood and of imbuing
it with a spirit or pneuma which is innate in all living substance,
so long as it remains alive, the _natural spirits_ (πνεῦμα φυσικόν,
_spiritus naturalis_ of the mediaevals). Charged with this, and also
with the nutritive material derived from the food, the venous blood is
distributed by the liver through the veins which arise from it in the
same way as the arteries from the heart. These veins carry nourishment
and _natural spirits_ to all parts of the body. _Iecur fons venarum_,
the liver as the source of the veins, remained through the centuries
the watchword of the Galenic physiology. The blood was held to ebb and
flow continuously in the veins during life.
[Illustration: FIG. 11. Illustrating Galen’s physiological teaching.]
Now from the liver arose one great vessel, the hepatic vein, from
division of which the others were held to come off as branches. Of
these branches, one, our _common vena cava_, entered the right side
of the heart. For the blood that it conveyed to the heart there were
two fates possible. The greater part remained awhile in the ventricle,
parting with its impurities and vapours, exhalations of the organs,
which were carried off by the _artery-like vein_ (φλὲπς ἀρτηριώδης,
the mediaeval _vena pulmonalis_, our pulmonary artery) to the lung
and then exhaled to the outer air. These impurities and vapours gave
its poisonous and suffocating character to the breath. Having parted
thus with its impurities, the venous blood ebbed back again from the
right ventricle into the venous system. But for a small fraction of
the venous blood that entered the right ventricle another fate was
reserved. This small fraction of venous blood, charged still with
the _natural spirits_ derived from the liver, passed through minute
channels in the septum between the ventricles and entered the left
chamber. Arrived there, it encountered the external pneuma and became
thereby elaborated into a higher form of spirit, the _vital spirits_
(πνεῦμα ζωτικόν, _spiritus vitalis_), which is distributed together
with blood by the arterial system to various parts of the body. In the
arterial system it also ebbed and flowed, and might be seen and felt to
pulsate there.
But among the great arterial vessels that sent forth arterial blood
thus charged with vital spirits were certain vessels which ascended
to the brain. Before reaching that organ they divided up into minute
channels, the _rete mirabile_ (πλέγμα μέγιστον θαῦμα), and passing
into the brain became converted by the action of that organ into a yet
higher type of spirits, the _animal spirits_ (πνεῦμα ψυχικόν, _spiritus
animalis_), an ethereal substance distributed to the various parts of
the body by the structures known to-day as nerves, but believed then to
be hollow channels. The three fundamental faculties (δυνάμεις), the
_natural_, the _vital_, and the _animal_, which brought into action the
corresponding functions of the body, thus originated as an expression
of the primal force or pneuma.
This physiology, we may emphasize, is not derived from an investigation
of human anatomy. In the human brain there is no _rete mirabile_,
though such an organ is found in the calf. In the human liver there
is no _hepatic vein_, though such an organ is found in the dog. Dogs,
calves, pigs, bears, and, above all, Barbary apes were freely dissected
by Galen and were the creatures from which he derived his physiological
ideas. Many of Galen’s anatomical and physiological errors are due to
his attributing to one creature the structures found in another, a fact
that only very gradually dawned on the Renaissance anatomists.
The whole knowledge possessed by the world in the department of
physiology from the third to the seventeenth century, nearly all the
biological conceptions till the thirteenth, and most of the anatomy and
much of the botany until the sixteenth century, all the ideas of the
physical structure of living things throughout the Middle Ages, were
contained in a small number of these works of Galen. The biological
works of Aristotle and Theophrastus lingered precariously in a few
rare manuscripts in the monasteries of the East; the total output of
hundreds of years of Alexandrian and Pergamenian activities was utterly
destroyed; the Ionian biological works, of which a sample has by a
miracle survived, were forgotten; but these vast, windy, ill-arranged
treatises of Galen lingered on. Translated into Latin, Syriac, Arabic,
and Hebrew, they saturated the intellectual world of the Middle Ages.
Commented on by later Greek writers, who were themselves in turn
translated into the same list of languages, they were yet again served
up under the names of such Greek writers as Oribasius, Paul of Aegina,
or Alexander of Tralles.
What is the secret of the vitality of these Galenic biological
conceptions? The answer can be given in four words. _Galen is a
teleologist_; and a teleologist of a kind whose views happened to fit
in with the prevailing theological attitude of the Middle Ages, whether
Christian, Moslem, or Jewish. According to him everything which exists
and displays activity in the human body originates in and is formed
by an intelligent being and on an intelligent plan, so that the organ
in structure and function is the result of that plan. ‘It was the
Creator’s infinite wisdom which selected the best means to attain his
beneficent ends, and it is a proof of His omnipotence that he created
every good thing according to His design, and thereby fulfilled His
will.’[89]
[89] A good instance of Galen’s teleological point of view is afforded
by his classical description of _the hand_ in the περὶ χρείας τῶν
ἐν ἀνθρώπου σώματι μορίων, _On the uses of the parts of the body of
man_, i. 1. This passage is available in English in a tract by Thomas
Bellott, London, 1840.
After Galen there is a thousand years of darkness, and biology ceases
to have a history. The mind of the Dark Ages turned towards theology,
and such remains of Neoplatonic philosophy as were absorbed into the
religious system were little likely to be of aid to the scientific
attitude. One department of positive knowledge must of course persist.
Men still suffered from the infirmities of the flesh and still sought
relief from them. But the books from which that advice was sought had
nothing to do with general principles nor with knowledge as such.
They were the most wretched of the treatises that still masqueraded
under the names of Hippocrates and Galen, mostly mere formularies,
antidotaries, or perhaps at best symptom lists. And, when the
depression of the western intellect had passed its worst, there was
still no biological material on which it could be nourished.
The prevailing interest of the barbarian world, at last beginning to
settle into its heritage of antiquity, was with Logic. Of Aristotle
there survived in Latin dress only the _Categories_ and the _De
interpretatione_, the merciful legacy of Boethius, the last of the
philosophers. Had a translation of Aristotle’s _Historia animalium_
or _De generatione animalium_ survived, had a Latin version of the
Hippocratic work _On generation_ or of the treatises of Theophrastus
_On plants_ reached the earlier Middle Ages, the whole mental history
of Europe might have been different and the rediscovery of nature might
have been antedated by centuries. But this was a change of heart for
which the world had long to wait; something much less was the earliest
biological gift of Greece. The gift, when it came, came in two forms,
one of which has not been adequately recognized, but both are equally
her legacy. These two forms are, firstly, the well-known work of the
early translators and, secondly, the tardily recognized work of certain
schools of minor art.
The earliest biological treatises that became accessible in the west
were rendered not from Greek but from Arabic. The first of them was
perhaps the treatise περὶ μυῶν κινήσεως, _On movement of muscles_ of
Galen, a work which contains more than its title suggests and indeed
sets forth much of the Galenic physiological system. It was rendered
into Latin from the Arabic of Joannitius (Hunain ibn Ishaq, 809-73),
probably about the year 1200, by one Mark of Toledo. It attracted
little attention, but very soon after biological works of Aristotle
began to become accessible. The first was probably the fragment _On
plants_. The Greek original of this is lost, and besides the Latin,
only an Arabic version of a former Arabic translation of a Syriac
rendering of a Greek commentary is now known! Such a work appeared from
the hand of a translator known as Alfred the Englishman about 1220 or a
little later. Neither it nor another work from the same translator, _On
the motion of the heart_, which sought to establish the primacy of that
organ on Aristotelian grounds, can be said to contain any of the spirit
of the master.[90]
[90] C. H. Haskins, ‘The reception of Arabic science in England,’
_English Historical Review_, London, 1915, p. 56.
A little better than these is the work of the wizard Michael the Scot
(1175?-1234?). Roger Bacon tells us that Michael in 1230 ‘appeared
[at Oxford], bringing with him the works of Aristotle in natural
history and mathematics, with wise expositors, so that the philosophy
of Aristotle was magnified among the Latins’. Scott produced his work
_De animalibus_ about this date and he included in it the three great
biological works of Aristotle, all rendered from an inferior Arabic
version.[91] Albertus Magnus (1206-80) had not as yet a translation
direct from the Greek to go upon for his great commentary on the
_History of animals_, but he depended on Scott. The biological works
of Aristotle were rendered into Latin direct from the Greek in the
year 1260 probably by William of Moerbeke.[92] Such translations,
appearing in the full scholastic age when everything was against
direct observation, cannot be said to have fallen on a fertile ground.
They presented an ordered account of nature and a good method of
investigation, but these were gifts to a society that knew little of
their real value.[93]
[91] The latest and best work on the Aristotelian translations of Scott
is an inaugural dissertation by A. H. Querfeld, _Michael Scottus und
seine Schrift, De secretis naturae_, Leipzig, 1919.
[92] J. G. Schneider, _Aristotelis de animalibus historiae_, Leipzig,
1811, p. cxxvi. L. Dittmeyer, _Guilelmi Moerbekensis translatio
commentationis Aristotelicae de generatione animalium_, Dillingen,
1915. L. Dittmeyer, _De animalibus historia_, Leipzig, 1907.
[93] The subject of the Latin translations of Aristotle is traversed
by A. and C. Jourdain, _Recherches critiques sur l’âge des
traductions latines d’Aristote_, 2nd ed., Paris, 1843; M. Grabmann,
_Forschungen über die lateinischen Aristoteles-Übersetzungen des
XIII. Jahrhunderts_, Münster i/W., 1916; and F. Wüstenfeld, _Die
Übersetzungen arabischer Werke in das Lateinische seit dem XI.
Jahrhundert_, Göttingen, 1877.
Yet the advent of these texts was coincident with a returning desire to
observe nature. Albert, with all his scholasticism, was no contemptible
naturalist. He may be said to have begun first-hand plant study in
modern times so far as literary records are concerned. His book _De
vegetabilibus_ contains excellent observations, and he is worthy
of inclusion among the fathers of botany. In his vast treatise _De
animalibus_, hampered as he is by his learning and verbosity, he shows
himself a true observer and one who has absorbed something of the
spirit of the great naturalist to whose works he had devoted a lifetime
of study and on which he professes to be commenting. We see clearly
the leaven of the Aristotelian spirit working, though Albert is still
a schoolman. We may select for quotation a passage on the generation
of fish, a subject on which some of Aristotle’s most remarkable
descriptions remained unconfirmed till modern times. These descriptions
impressed Albert in the same way as they do the modern naturalist. To
those who know nothing of the stimulating power of the Aristotelian
biological works, Albert’s description of the embryos of fish and his
accurate distinction of their mode of development from that of birds,
by the absence of an allantoic membrane in the one and its presence
in the other, must surely be startling. Albert depends on Aristotle—a
third-hand version of Aristotle—but does not slavishly follow him.
‘Between the mode of development (_anathomiam generationis_) of birds’
and fishes’ eggs there is this difference: during the development of
the fish the second of the two veins which extend from the heart [as
described by Aristotle in birds] does not exist. For we do not find
the vein which extends to the outer covering in the eggs of birds
which some wrongly call the navel because it carries the blood to the
exterior parts; but we do find the vein that corresponds to the yolk
vein of birds, for this vein imbibes the nourishment by which the limbs
increase.... In fishes as in birds, channels extend from the heart
first to the head and the eyes, and first in them appear the great
upper parts. As the growth of the young fish increases the albumen
decreases, being incorporated into the members of the young fish, and
it disappears entirely when development and formation are complete. The
beating of the heart ... is conveyed to the lower part of the belly,
carrying pulse and life to the inferior members.
‘While the young [fish] are small and not yet fully developed they have
veins of great length which take the place of the navel-string, but as
they grow and develop, these shorten and contract into the body towards
the heart, as we have said about birds. The young fish and the eggs are
enclosed and in a covering, as are the eggs and young of birds. This
covering resembles the dura mater [of the brain], and beneath it is
another [corresponding therefore to the pia mater of the brain] which
contains the young animal and nothing else.’[94]
In the next century Conrad von Megenberg (1309-98) produced his _Book
of Nature_, a complete work on natural history, the first of the kind
in the vernacular, founded on Latin versions, now rendered direct
from the Greek, of the Aristotelian and Galenic biological works. It
is well ordered and opens with a systematic account of the structure
and physiology of man as a type of the animal creation, which is then
systematically described and followed by an account of plants. Conrad,
though guided by Aristotle, uses his own eyes and ears, and with him
and Albert the era of direct observation has begun.[95]
[94] The enormous _De Animalibus_ of Albert of Cologne is now available
in an edition by H. Stadler, _Albertus Magnus De Animalibus Libri
XXVI nach der cölner Urschrift_, 2 vols., Münster i/W., 1916-21. The
quotation is translated from vol. i, pp. 465-6.
[95] Conrad’s work is conveniently edited by H. Schultz, _Das Buch der
Natur von Conrad von Megenberg, die erste Naturgeschichte in deutscher
Sprache, in Neu-Hochdeutsche Sprache bearbeitet_, Greifswald, 1897.
Conrad’s work is based on that of Thomas of Cantimpré (1201-70).
But there was another department in which the legacy of Greece found
an even earlier appreciation. For centuries the illustrations to
herbals and bestiaries had been copied from hand to hand, continuing
a tradition that had its rise with Greek artists of the first century
B. C. But their work, copied at each stage without reference to the
object, moved constantly farther from resemblance to the original. At
last the illustrations became little but formal patterns, a state in
which they remained in some late copies prepared as recently as the
sixteenth century. But at a certain period a change set in, and the
artist, no longer content to rely on tradition, appeals at last to
nature. This new stirring in art corresponds with the new stirring in
letters, the Arabian revival—itself a legacy of Greece, though sadly
deteriorated in transit—that gave rise to scholasticism. In much of the
beautiful carved and sculptured work of the French cathedrals the new
movement appears in the earlier part of the thirteenth century. At such
a place as Chartres we see the attempt to render plants and animals
faithfully in stone as early as 1240 or before. In the easier medium of
parchment the same tendency appears even earlier. When once it begins
the process progresses slowly until the great recovery of the Greek
texts in the fifteenth century, when it is again accelerated.
During the sixteenth century the energy of botanists and zoologists was
largely absorbed in producing most carefully annotated and illustrated
editions of Dioscorides and Theophrastus and accounts of animals,
habits, and structure that were intended to illustrate the writings of
Aristotle, while the anatomists explored the bodies of man and beast
to confirm or refute Galen. The great monographs on birds, fishes, and
plants of this period, ostensibly little but commentaries on Pliny,
Aristotle, and Dioscorides, represent really the first important
efforts of modern times at a natural history. They pass naturally into
the encyclopaedias of the later sixteenth century, and these into the
physiological works of the seventeenth. Aristotle was never a dead hand
in Biology as he was in Physics, and this for the reason that he was a
great biologist but was not a great physicist.
With the advance of the sixteenth century the works of Aristotle, and
to a less extent those of Dioscorides and Galen, became the great
stimulus to the foundation of a new biological science. Matthioli
(1520-77), in his commentary on Dioscorides (first edition 1544), which
was one of the first works of its type to appear in the vernacular,
made a number of first-hand observations on the habits and structure
of plants that is startling even to a modern botanist. About the same
time Galenic physiology, expressed also in numerous works in the
vulgar tongue and rousing the curiosity of the physicians, became the
clear parent of modern physiology and comparative anatomy. But, above
all, the Aristotelian biological works were fertilizers of the mind.
It is very interesting to watch a fine observer such as Fabricius ab
Acquapendente (1537-1619) laying the foundations of modern embryology
in a splendid series of first-hand observations, treating his own great
researches almost as a commentary on Aristotle. What an impressive
contrast to the arid physics of the time based also on Aristotle! ‘My
purpose’, says Fabricius, ‘is to treat of the formation of the foetus
in every animal, setting out from that which proceeds from the egg: for
this ought to take precedence of all other discussion of the subject,
both because it is not difficult to make out Aristotle’s view of the
matter, and because his treatise on the Formation of the Foetus from
the egg is by far the fullest, and the subject is by much the most
extensive and difficult.’[96]
[96] Hieronimo Fabrizio of Acquapendente, _De formato foetu_, Padua,
1604.
The industrious and careful Fabricius, with a wonderful talent for
observation lit not by his own lamp but by that of Aristotle, bears
a relation to the master much like that held by Aristotle’s pupil
in the flesh, Theophrastus. The works of the two men, Fabricius and
Theophrastus, bear indeed a resemblance to each other. Both rely
on the same group of general ideas, both progress in much the same
ordered calm from observation to observation, both have an inspiration
which is efficient and stimulating but below the greatest, both are
enthusiastic and effective as investigators of fact, but timid and
ineffective in drawing conclusions.
But Fabricius was more happy in his pupils than Theophrastus, for
we may watch the same Aristotelian ideas fermenting in the mind of
Fabricius’s successor, the greatest biologist since Aristotle himself,
William Harvey (1578-1657).[97] This writer’s work _On generation_ is a
careful commentary on Aristotle’s work on the same topic, but it is a
commentary not in the old sense but in the spirit of Aristotle himself.
Each statement is weighed and tested in the light of experience, and
the younger naturalist, with all his reverence for Aristotle, does not
hesitate to criticize his conclusions. He exhibits an independence of
thought, an ingenuity in experiment, and a power of deduction that
places his treatise as the middle term of the three great works on
embryology of which the other members are those of Aristotle and Karl
Ernst von Baer (1796-1870).[98]
[97] William Harvey, _Exercitationes de generatione animalium_, London,
1651.