THE CONTINUITY OF SCIENCE--THE MEDIEVAL CHURCH AND THE ARABS
Learning has very often and very aptly been compared to a torch passed
from hand to hand. By the written sign or spoken word it is transmitted
from one person to another. Very little advance in culture could be made
even by the greatest man of genius if he were dependent, for what
knowledge he might acquire, merely on his own personal observation.
Indeed, it might be said that exceptional mental ability involves a
power to absorb the ideas of others, and even that the most original
people are those who are able to borrow the most freely.
In recalling the lives of certain great men we may at first be inclined
to doubt this truth. How shall we account for the part played in the
progress of civilization by the rustic Burns, the village-bred
Shakespeare, or by Lincoln the frontiersman? When, however, we
scrutinize the case of any one of these, we discover, of course,
exceptional natural endowment, susceptibility to mental influence,
remarkable powers of acquisition, but no ability to produce anything
absolutely original. In the case of Lincoln, for example, we find that
in his youth he was as distinguished by diligence in study as by
physical stature and prowess. After he withdrew from school, he read,
wrote, and ciphered (in the intervals of manual work) almost
incessantly. He read everything he could lay hands on. He copied out
what most appealed to him. A few books he read and re-read till he had
almost memorized them. What constituted his library? The Bible, _Æsop's
Fables_, _Robinson Crusoe_, _The Pilgrim's Progress_, a _Life of
Washington_, a _History of the United States_. These established for him
a vital relation with the past, and laid the foundations of a democratic
culture; not the culture of a Chesterfield, to be sure, but something
immeasurably better, and none the less good for being almost universally
accessible. Lincoln developed his logical powers conning the dictionary.
Long before he undertook the regular study of the law, he spent long
hours poring over the revised statutes of the State in which he was
living. From a book he mastered with a purpose the principles of
grammar. In the same spirit he learned surveying, also by means of a
book. There is no need to ignore any of the influences that told
toward the development of this great statesman, the greatest of
English-speaking orators, but it is evident that remote as was his
habitation from all the famous centers of learning he was, nevertheless,
early immersed in the current of the world's best thought.
Similarly, in the history of science, every great thinker has his
intellectual pedigree. Aristotle was the pupil of Plato, Plato was the
disciple of Socrates, and the latter's intellectual genealogy in turn
can readily be traced to Thales, and beyond--to Egyptian priests and
Babylonian astronomers.
The city of Alexandria, founded by the pupil of Aristotle in 332 B.C.,
succeeded Athens as the center of Greek culture. On the death of
Alexander the Great, Egypt was ruled by one of his generals, Ptolemy,
who assumed the title of king. This monarch, though often engaged in
war, found time to encourage learning, and drew to his capital scholars
and philosophers from Greece and other countries. He wrote himself a
history of Alexander's campaigns, and instituted the famous library of
Alexandria. This was greatly developed (and supplemented with schools of
science and an observatory) by his son Ptolemy Philadelphus, a prince
distinguished by his zeal in promoting the good of the human species. He
collected vast numbers of manuscripts, had strange animals brought from
distant lands to Alexandria, and otherwise promoted scientific research.
This movement was continued under Ptolemy III (246-221 B.C.).
Something has already been said of the early astronomers and
mathematicians of Alexandria. The scientific movement of the later
Alexandrian period found its consummation in the geographer, astronomer,
and mathematician Claudius Ptolemy (not to be confused with the rulers
of that name). He was most active 127-151 A.D., and is best known by his
work the _Syntaxis_, which summarized what was known in astronomy at
that time. Ptolemy drew up a catalogue of 1080 stars based on the
earlier work of Hipparchus. He followed that astronomer in teaching that
the earth is the center of the movement of the heavenly bodies, and this
geocentric system of the heavens became known as the Ptolemaic system of
astronomy. To Hipparchus and Ptolemy we owe also the beginnings of the
science of trigonometry. The _Syntaxis_ sets forth his method of
drawing up a table of chords. For example, the side of a hexagon
inscribed in a circle is equal to the radius, and is the chord of 60°,
or of the sixth part of the circle. The radius is divided into sixty
equal parts, and these again divided and subdivided sexagesimally. The
smaller divisions and the subdivisions are known as prime minute parts
and second minute parts (_partes minutæ primæ_ and _partes minutæ
secundæ_), whence our terms "minute" and "second." The sexagesimal
method of dividing the circle and its parts was, as we have seen in the
first chapter, of Babylonian origin.
Ptolemy was the last of the great Greek astronomers. In the fourth
century and at the beginning of the fifth, Theon and his illustrious
daughter Hypatia commented on and taught the astronomy of Ptolemy. In
the Greek schools of philosophy Plato's doctrine of the supreme reality
of the invisible world was harmonized for a time with Christian
mysticism, but these schools were suppressed at the beginning of the
sixth century. The extinction of scientific and of all other learning
seemed imminent.
What were the causes of this threatened break in the historical
continuity of science? They were too many and too varied to admit of
adequate statement here. From the latter part of the fourth century the
Roman Empire had been overrun by the Visigoths, the Vandals, the Huns,
the Ostrogoths, the Lombards, and other barbarians. Even before these
incursions learning had suffered under the calamity of war. In the time
of Julius Cæsar the larger of the famous libraries of Alexandria,
containing, it is computed, some 490,000 rolls, caught fire from ships
burning in the harbor, and perished. This alone involved an incalculable
setback to the march of scientific thought.
Another influence tending to check the advance of the sciences was the
clash between Christian and Pagan ideals. To many of the bishops of the
Church the aims and pursuits of science seemed vain and trivial when
compared with the preservation of purity of character or the assurance
of eternal felicity. Many were convinced that the end of the world was
at hand, and strove to fix their thoughts solely on the world to come.
Their austere disregard of this life found some support in a noble
teaching of the Stoic philosophy that death itself is no evil to the
just man. The early Christian teachers held that the body should be
mortified if it interfered with spiritual welfare. Disease is a
punishment, or a discipline to be patiently borne. One should choose
physical uncleanliness rather than run any risk of moral contamination.
It is not impossible for enlightened people at the present time
to assume a tolerant attitude toward the worldly Greeks or the
other-worldly Christians. At that time, however, mutual antipathy was
intense. The long and cruel war between science and Christian theology
had begun.
Not all the Christian bishops, to be sure, took a hostile view of Greek
learning. Some regarded the great philosophers as the allies of the
Church. Some held that churchmen should study the wisdom of the Greeks
in order the better to refute them. Others held that the investigation
of truth was no longer necessary after mankind had received the
revelation of the gospel. One of the ablest of the Church Fathers
regretted his early education and said that it would have been better
for him if he had never heard of Democritus. The Christian writer
Lactantius asked shrewdly whence atoms came, and what proof there was of
their existence. He also allowed himself to ridicule the idea of the
antipodes, a topsy-turvy world of unimaginable disorder. In 389 A.D. one
of the libraries at Alexandria was destroyed and its books were pillaged
by the Christians. In 415 Hypatia, Greek philosopher and mathematician,
was murdered by a Christian mob. In 642 the Arabs having pushed their
conquest into northern Africa gained possession of Alexandria. The cause
of learning seemed finally and irrecoverably lost.
The Arab conquerors, however, showed themselves singularly hospitable to
the culture of the nations over which they had gained control. Since the
time of Alexander there had been many Greek settlers in the larger
cities of Syria and Persia, and here learning had been maintained in the
schools of the Jews and of a sect of Christians (Nestorians), who were
particularly active as educators from the fifth century to the eleventh.
The principal Greek works on science had been translated into Syrian.
Hindu arithmetic and astronomy had found their way into Persia. By the
ninth century all these sources of scientific knowledge had been
appropriated by the Arabs. Some fanatics among them, to be sure, held
that one book, the Koran, was of itself sufficient to insure the
well-being of the whole human race, but happily a more enlightened view
prevailed.
In the time of Harun Al-Rashid (800 A.D.), and his son, the Caliphate
of Bagdad was the center of Arab science. Mathematics and astronomy were
especially cultivated; an observatory was established; and the work of
translation was systematically carried on by a sort of institute of
translators, who rendered the writings of Aristotle, Hippocrates, Galen,
Euclid, Ptolemy, and other Greek scientists, into Arabic. The names of
the great Arab astronomers and mathematicians are not popularly known to
us; their influence is greater than their fame. One of them describes
the method pursued by him in the ninth century in taking measure of the
circumference of the earth. A second developed a trigonometry of sines
to replace the Ptolemaic trigonometry of chords. A third made use of the
so-called Arabic (really Hindu) system of numerals, and wrote the first
work on Algebra under that name. In this the writer did not aim at the
mental discipline of students, but sought to confine himself to what is
easiest and most useful in calculation, "such as men constantly require
in cases of inheritance, legacies, partition, law-suits, and trade, and
in all their dealings with one another, or where the measuring of lands,
the digging of canals, geometrical computation, and other objects of
various sorts and kinds are concerned."
In the following centuries Arab institutions of higher learning were
widely distributed and the flood-tide of Arab science was borne farther
west. At Cairo about the close of the tenth century the first accurate
records of eclipses were made, and tables were constructed of the
motions of the sun, moon, and planets. Here as elsewhere the Arabs
displayed ingenuity in the making of scientific apparatus, celestial
globes, sextants of large size, quadrants of various sorts, and
contrivances from which in the course of time were developed modern
surveying instruments for measuring horizontal and vertical angles.
Before the end of the eleventh century an Arab born at Cordova, the
capital of Moorish Spain, constructed the Toletan Tables. These were
followed in 1252 by the publication of the Alphonsine Tables, an event
which astronomers regard as marking the dawn of European science.
Physics and chemistry, as well as mathematics and astronomy, owe much in
their development to the Arabs. An Arabian scientist of the eleventh
century studied the phenomena of the reflection and refraction of light,
explained the causes of morning and evening twilight, understood the
magnifying power of lenses and the anatomy of the human eye. Our use of
the terms retina, cornea, and vitreous humor may be traced to
the translation of his work on optics. The Arabs also made fair
approximations to the correct specific weights of gold, copper, mercury,
and lead. Their alchemy was closely associated with metallurgy, the
making of alloys and amalgams, and the handicrafts of the goldsmiths and
silversmiths. The alchemists sought to discover processes whereby one
metal might be transmuted into another. Sulphur affected the color and
substance. Mercury was supposed to play an important part in metal
transmutations. They thought, for example, that tin contained more
mercury than lead, and that the baser, more unhealthy metal might be
converted into the nobler and more healthy by the addition of mercury.
They even sought for a substance that might effect all transmutations,
and be for mankind a cure for all ailments, even that of growing old.
The writings that have been attributed to Geber show the advances that
chemistry made through the experiments of the Arabs. They produced
sulphuric and nitric acids, and _aqua regia_, able to dissolve gold, the
king of metals. They could make use of wet methods, and form metallic
salts such as silver nitrate. Laboratory processes like distilling,
filtering, crystallization, sublimation, became known to the Europeans
through them. They obtained potash from wine lees, soda from sea-plants,
and from quicksilver the mercuric oxide which played so interesting a
part in the later history of chemistry.
Much of the science lore of the Arabs arose from their extensive trade,
and in the practice of medicine. They introduced sugar-cane into Europe,
improved the methods of manufacturing paper, discovered a method of
obtaining alcohol, knew the uses of gypsum and of white arsenic, were
expert in pharmacy and learned in materia medica. They are sometimes
credited with introducing to the West the knowledge of the mariner's
compass and of gunpowder.
Avicenna (980-1037), the Arab physician, not only wrote a large work on
medicine (the _Canon_) based on the lore of Galen, which was used as a
text-book for centuries in the universities of Europe, but wrote
commentaries on all the works of Aristotle. For Averroës (1126-1198),
the Arab physician and philosopher, was reserved the title "The
Commentator," due to his devotion to the works of the Greek biologist
and philosopher. It was through the commentaries of Averroës that
Aristotelian science became known in Europe during the Middle Ages. In
his view Aristotle was the founder and perfecter of science; yet he
showed an independent knowledge of physics and chemistry, and wrote on
astronomy and medicine as well as philosophy. He set forth the facts in
reference to natural phenomena purely in the interests of the truth. He
could not conceive of anything being created from nothing. At the same
time he taught that God is the essence, the eternal cause, of progress.
It is in humanity that intellect most clearly reveals itself, but there
is a transcendent intellect beyond, union with which is the highest
bliss of the individual soul. With the death of the Commentator the
culture of liberal science among the Arabs came to an end, but his
influence (and through him that of Aristotle) was perpetuated in all the
western centers of education.
The preservation of the ancient learning had not, however, depended
solely on the Arabs. At the beginning of the sixth century, before the
taking of Alexandria by the followers of Mohammed, St. Benedict had
founded the monastery of Monte Cassino in Italy. Here was begun the
copying of manuscripts, and the preparation of compendiums treating of
grammar, dialectic, rhetoric, arithmetic, astronomy, music, and
geometry. These were based on ancient, Roman writings. Works like
Pliny's _Natural History_, the encyclopedia of the Middle Ages, had
survived all the wars by which Rome had been devastated. Learning, which
in Rome's darkest days had found refuge in Britain and Ireland, returned
book in hand. Charlemagne (800) called Alcuin from York to instruct
princes and nobles at the Frankish court. At this same palace school
half a century later the Irishman Scotus Erigena exhibited his learning,
wit, and logical acumen. In the tenth century Gerbert (Pope Sylvester
II) learned mathematics at Arab schools in Spain. The translation of
Arab works on science into the Latin language, freer intercourse of
European peoples with the East through war and trade, economic
prosperity, the liberation of serfs and the development of a well-to-do
middle class, the voyages of Marco Polo to the Orient, the founding of
universities, the encouragement of learning by the Emperor Frederick II,
the study of logic by the schoolmen, were all indicative of a new era in
the history of scientific thought.
The learned Dominican Albertus Magnus (1193-1280) was a careful student
of Aristotle as well as of his Arabian commentators. In his many books
on natural history he of course pays great deference to the Philosopher,
but he is not devoid of original observation. As the official visitor of
his order he had traveled through the greater part of Germany on foot,
and with a keen eye for natural phenomena was able to enrich botany and
zoölogy by much accurate information. His intimacy with the details of
natural history made him suspected by the ignorant of the practice of
magical arts.
His pupil and disciple Thomas Aquinas (1227-1274) was the philosopher
and recognized champion of the Christian Church. In 1879 Pope Leo XIII,
while proclaiming that every wise saying, every useful discovery, by
whomsoever it may be wrought, should be welcomed with a willing and
grateful mind, exhorted the leaders of the Roman Catholic Church to
restore the golden wisdom of St. Thomas and to propagate it as widely as
possible for the good of society and the advancement of all the
sciences. Certainly the genius of St. Thomas Aquinas seems comprehensive
enough to embrace all science as well as all philosophy from the
Christian point of view. According to him there are two sources of
knowledge, reason and revelation. These are not irreconcilably opposed.
The Greek philosophers speak with the voice of reason. It is the duty of
theology to bring all knowledge into harmony with the truths of
revelation imparted by God for the salvation of the human race. Averroës
is in error when he argues the impossibility of something being created
from nothing, and again when he implies that the individual intellect
becomes merged in a transcendental intellect; for such teaching would be
the contrary of what has been revealed in reference to the creation of
the world and the immortality of the individual soul. In the
accompanying illustration we see St. Thomas inspired by Christ in glory,
guided by Moses, St. Peter, and the Evangelists, and instructed by
Aristotle and Plato. He has overcome the heathen philosopher Averroës,
who lies below discomfited.
[Illustration: ST. THOMAS AQUINAS OVERCOMING AVERROËS]
The English Franciscan Roger Bacon (1214-1294) deserves to be mentioned
with the two great Dominicans. He was acquainted with the works of the
Greek and Arabian scientists. He transmitted in a treatise that fell
under the eye of Columbus the view of Aristotle in reference to the
proximity of another continent on the other side of the Atlantic; he
anticipated the principle on which the telescope was afterwards
constructed; he advocated basing natural science on experience and
careful observation rather than on a process of reasoning. Roger Bacon's
writings are characterized by a philosophical breadth of view. To his
mind the earth is only an insignificant dot in the center of the vast
heavens.
In the centuries that followed the death of Bacon the relation of this
planet to the heavenly bodies was made an object of study by a
succession of scientists who like him were versed in the achievements of
preceding ages. Peurbach (1423-1461), author of _New Theories of the
Planets_, developed the trigonometry of the Arabians, but died before
fulfilling his plan to give Europe an epitome of the astronomy of
Ptolemy. His pupil, Regiomontanus, however, more than made good the
intentions of his master. The work of Peurbach had as commentator the
first teacher in astronomy of Copernicus (1473-1543). Later Copernicus
spent nine years in Italy, studying at the universities and acquainting
himself with Ptolemaic and other ancient views concerning the motions of
the planets. He came to see that the apparent revolution of the heavenly
bodies about the earth from east to west is really owing to the
revolution of the earth on its axis from west to east. This view was so
contrary to prevailing beliefs that Copernicus refused to publish his
theory for thirty-six years. A copy of his book, teaching that our earth
is not the center of the universe, was brought to him on his deathbed,
but he never opened it.
Momentous as was this discovery, setting aside the geocentric system
which had held captive the best minds for fourteen slow centuries and
substituting the heliocentric, it was but a link in the chain of
successes in astronomy to which Tycho Brahe, Kepler, Galileo, Newton,
and their followers contributed.
REFERENCES
_The Catholic Encyclopedia._
J. L. E. Dreyer, _History of the Planetary Systems_.
_Encyclopædia Britannica._ Arabian Philosophy; Roger Bacon.
W. J. Townsend, _The Great Schoolmen of the Middle Ages_.
R. B. Vaughan, _St. Thomas of Aquin; his Life and Labours_.
Andrew D. White, _A History of the Warfare of Science with Theology in
Christendom_.