FOUNDING OF SYSTEMATIC SCIENCE IN GREECE
The world is indebted to the Greeks as much for science as for art and
literature. The idealistic spirit of ancient Greece invested scientists
as well as poets, artists, and thinkers generally. But the Greek
scientists were students in the great schools of Egypt and brought
much of their knowledge from that country. The greatest contributions
made by Greece were in the nature of methods and analysis. They were
led to these by the tendencies of the Greek mind to abstract thought
and philosophical investigations. They soon recognized that science
is knowledge gained by certain methods of abstraction. Data had to
be systematically collected, digested, classified, and impartially
studied. The results of such studies had to be assembled and expressed
in the most useful forms. Progress had to be made by the trial and
error method and the results of experiments tested by synthesis as well
as analysis; by induction as well as deduction.
The Ionian philosophers were the first to break away from the
mythological traditions surrounding the principles of Egyptian and
Asiatic science. Thales of Miletus about the year 580 B. C. taught
that there is an essence, force, or soul in all things. This universal
principle of activity is superhuman. Seeking to find of what the
world is made, he arrived at the idea that water, or moisture, is the
basic element. All matter, he said, is water in various forms and
combinations. Here we see scientific knowledge sought with a definite
aim and with unity of purpose. None of the earlier peoples had ever
attempted to approach knowledge in this logical and fruitful manner.
When the learned Babylonians were asked what the earth was they simply
said: "When the world was created, Marduk, the sun god, took Tiamat, or
Chaos, and divided her. The sky was formed above and the earth below."
And the Egyptians answered the question in a similar way by saying:
"When the world was created, Shu tore the goddess Nuit from the arms of
Keb, and now she hangs above him and he is the earth."
It was this kind of statement that Thales cast aside. He sought for
more concrete definitions. Customary beliefs were not acceptable to
him; his knowledge must be based on reason. Here we see the dawn
of a new scientific spirit and the beginning of a new method of
investigating knowledge. The world was introduced to a new field of
intellectual activities.
The theory of Thales was studied by other Greek philosophers. But
Anaximander, a friend of Thales, rejected it, and in its place
suggested that there is one eternal, indestructible substance which
constitutes the basis of matter. This was not water but an infinite
eternal motion. Water is subjected to extremes of temperature. Under
such conditions nothing could have been stable enough to constitute
matter. A primary substance must be free from warring or antagonistic
elements.
The world arose, said Anaximander, through the evolution of a substance
subjected to temperature changes which developed from the eternal,
boundless, basic element. A sphere of flame arose from this, as from
an explosion, and assumed a rounded form with concentric divisions. As
these rings became detached, the sun, moon, stars, and other heavenly
bodies and the earth were formed. Aristotle tells us that, according
to Anaximander's theory, the terrestrial region was at first moist;
and, as the moisture was dried up by the sun, the portion that was
evaporated produced the winds and the turnings of the sun and moon, the
remaining portion becoming the sea. In time the sea, Anaximander held,
would dry up. The heat, or fire, of the world would burn the whole of
the cold moist element. Then the world would become a mixture of heat
and cold like the boundless, primary element surrounding it, and by
which it would be absorbed.
This theory of matter and the evolution of the world marks a notable
advance over any previous scientific theory. It was well developed by
numerous teachers of the Milesian philosophical school and has played a
great rôle in intellectual history.
The daring nature of some of Anaximander's explanations of earthly
organisms may be realized from a sketch of his views on the evolution
of animals. He taught that living creatures arose from the moist
element as it was evaporated by the sun. Man at first resembled a fish.
All animals were developed in the moisture wrapped in a protecting
cover or bark. As they advanced in age, they came out into a drier
atmosphere and discarded their protective coats. Man was not an
original creation, but resulted from the fusion of other species.
Anaximander's reason for this statement was that the period of infancy
of the human being is so long that had he been born that way originally
he could not have survived. There must have been a slow development
from ancient ancestors. This may be regarded as an anticipation of
the Darwinian theory. Thus man's thoughts in succeeding ages have a
rhythmic swing.
Anaximenes rejected some of Anaximander's ideas and furnished new
ones to take their places. He was not so daring a thinker as his
predecessor, and his theory of the world was not as interesting as
Anaximander's. Many of his teachings, however, are accepted as sound
to-day.
Anaximenes contended that the basic element was not boundless, but
determinate. Innumerable substances are derivable from it and, just as
our soul, like an atmosphere, holds us together, so do breath and air
encompass the whole world. Air is always in motion, otherwise so many
changes could not be made by it. It differs in various substances in
virtue of its rarefaction and condensation.
The perpetual changes taking place in the world owing to the
instability of matter were emphasized by Heraclitus. He taught that
there is nothing immutable in the world process excepting the law or
principle which governs it.
Cosmological speculations were not the only ones attracting the
attention of the Greek scientists. Pythagoras, for example, founded a
philosophical college devoted to mathematical studies which resulted
in the development of arithmetic to points beyond the requirements of
commerce. He made arithmetic the basis of a profound philosophical
system.
Pythagoras studied science in Egypt and first became familiar with
Egyptian and Babylonian mathematics and geometry. He also studied
the Milesian cosmological philosophy. On his return to Greece from
his foreign studies he sought to discover a principle of homogeneity
in the universe more acceptable than any suggested by the earlier
philosophers. He had noticed numerous relationships between numbers
and natural phenomena, and believed that the true basis of philosophy
was to be found in numbers. In seeking data to sustain this thesis, he
discovered harmonic progression. His experiments showed that when harp
strings of equal length were stretched by weights having the proportion
of ½:⅔:¾, they produced harmonic intervals of an octave, a fifth and
a fourth apart. Since he saw that harmony of sounds depended upon
proportion he concluded that order and beauty in the world originate
in numbers. There are seven intervals in a musical scale, and seven
planets sweeping the heavens. Seven must, therefore, be a basic number.
This suggested to him his ideas regarding the harmony of the spheres.
Pythagoras and his students found that the sum of a series of odd
numbers from 1 to 2n+1 was always a complete square. When even numbers
are added to the above series we get 2, 6, 12, 20, etc., in which every
member can be broken into two factors differing from each other by
unity. Thus 6 = 2.3, 12 = 3.4, 20 = 4.5, etc. Such numbers were called
heteromecic. Numbers like n(n+1)⁄₂ were called triangular. A large
number of other arithmetical relations were found and given distinctive
names. The Pythagoreans were also familiar with the principles of
arithmetical, geometrical, harmonic, and musical proportion.
[Illustration: DE WITT CLINTON TRAIN OF 1831 BESIDE A MODERN
LOCOMOTIVE]
[Illustration: LOCOMOTIVE OF THE 1870 PERIOD STILL IN USE IN THE OZARKS]
[Illustration: "JOHN BULL," A LOCOMOTIVE BROUGHT FROM ENGLAND AND PUT
INTO SERVICE IN AMERICA IN 1831]
Pythagoras made similar advances in geometry. He believed that each
arithmetical fact had an analogue in geometry, and each geometrical
fact a counterpart in arithmetic. He devised a rule by which integral
numbers could be found so that the sum of the squares of two of them
equaled the square of the third. He also developed the theory of
irrational quantities. The first incommensurable ratio discovered is
said to have been that of the side of a square to its diagonal which is
1:√2̅.
Euclid (300 B. C.) developed this theory in the tenth book of his
geometry as still used.
Pythagoras not only placed mathematics on a solid scientific basis, he
also established the fact that the physical phenomena of the world are
governed by mathematical laws.
Little progress appears to have been made in astronomy by the Greeks in
the time of Pythagoras. The Milesians and the associates of Pythagoras
advanced numerous theories, but none of these was better than some
of the Egyptian ideas. Hicetas, and others of this period, believed
that the sun, moon, stars, and all other bodies in the heavens were
stationary and that only the earth moved. The great turning movement
of the earth around its axis produced the illusion that it was the
heavenly bodies which were moving while the earth remained stationary.
The astronomical theories of Pythagoras, Hicetas, and Philolaus, all
affirmed that the universe is composed of the elements earth, air,
fire, and water, the whole mass being of spherical shape with the earth
at the center and all having life or motion. These early theories,
2,000 years later, did service by aiding to secure acceptance for the
Copernican theory. The Pythagorean ideas that the universe is one
grand harmonious system, and that thought instead of sense is the sole
criterion of truth, have exercised important influence on intellectual
speculation throughout the ages.
In order to collect data for testing their theories in the physical and
mathematical sciences, the Greeks invented many physical appliances.
The monochord, employed in determining the relationships of vibrating
harmonic strings is one of the first mechanisms used in practical
physics that we have definite information about. An anvil, metal and
glass disks, and bell-shaped cylinders were employed in studying the
movements of sound waves.
Alcmæon (508 B. C.) was one of the earliest of the Greek anatomists. He
was a disciple of Pythagoras and employed the logical research methods
of his teacher in the investigation of medical problems. Although
the Egyptians had developed medical science to a considerable extent
and had taught the Greeks, their methods were not based upon sound
principles. The result was that the more analytically minded Greeks
could not accept certain Egyptian ideas. The Egyptian anatomical
teachings were particularly crude, and Alcmæon began to investigate
that science. His discoveries, both in anatomy and physiology, were
very great. He outlined the functions of the principal organs of the
body, discovered the optic nerve, the difference between the arterial
and nervous systems, the Eustachian tube, the two divisions of the
brain, the nerves connecting the brain with the organs of sense and
with the spinal column. These advances placed the medical sciences
on a logical basis similar to that of the physical, mathematical, and
astronomical sciences. This first great anatomist and physiologist
invented the practice of anatomical dissection and surgical
exploration, and advanced the practice of medicine to a higher degree
of usefulness.
After the Greeks had satisfied themselves that they possessed a
cosmological theory which answered the demands of reason they turned
their investigations to the question of how matter was changed into
its innumerable forms. Empedocles had taught that when the primary
elements, earth, air, fire, and water, were mixed in variable
proportions they yielded different kinds of matter. Leucippus,
Democritus, Anaxagoras, and others studied the subject more carefully
and developed a novel theory. When matter is divided as far as possible
do the ratios of the constituents remain the same? This problem
attracted their attention. They also asked themselves whether there was
not a simpler conception to explain the basic state of matter. When
they began their inquiries, the qualities of matter were believed to
reflect their essences. For example, the sweetness of honey and the
color of the sky were real things which should be studied in themselves
apart from honey and the sky. Democritus thought, however, that such
changes of color as the sky undergoes at dawn and sunset would not
take place if the colors were real elementary things. While meditating
on this the thought arose in their mind: "If we assume matter to be
composed of an infinite number of minutest particles or atoms, could we
not explain the changes in matter by changes in atomic quantities and
orders?" This line of thought resulted in the development of the atomic
theory and the origin of the philosophic school of the atomists.
According to Leucippus some of the atoms darting about in the universe
collide and thus give rise to new substances. He also believed that
the atoms followed whirling or circular paths and that such rotary
motions drew in neighboring atoms, and that as these movements
continued indefinitely within the atoms the constituents were being
constantly rearranged, the lighter elements being grouped around the
periphery; the heavier ones around the center. These changes were due
to pressure and impact. These conceptions about atoms were carried
into cosmological discussions and it was taught that there are various
worlds and planets within the boundless universe, each one moving
freely according to physical laws, unless fractured by collision with
another.
Zeno challenged these doctrines because of the importance attached to
the whirling motion. He attempted to show that such atomic motions
are impossible. His proofs of the impossibility of atomic motion were
designed with the object of sustaining his own theory of an ultimate
principle of unity. His mental trend was toward negation. Whenever his
rival Parmenides argued affirmatively regarding a scientific principle,
Zeno would invariably maintain the negative side of the question.
Zeno's first proof of the impossibility of motion referred to the
impossibility of passing through a fixed space. He showed that by
dividing a line into an infinite number of parts an infinite number of
points would be obtained and these permitted no beginning of motion.
His second proof tried to show the impossibility of passing through
space having movable boundaries. The story of Achilles and the
tortoise illustrates this. A pursuer in a race at every interval must
reach a point from which the pursued starts simultaneously. But the
latter is always in advance.
The third, or "resting arrow," argument showed that a moving arrow
is at every instant in some one point of its track. Its movement at
such instant is then equal to zero. Its track is a group of zeros. No
magnitude could be framed from these.
Zeno also anticipated much later philosophical discussions, like
Einstein's, relating to the relativity of motion. He took for an
example a moving wagon. Its movement would appear different to
observers on other moving bodies going in various directions. They
would see changes in rates of speed as well as in direction.
Protagoras, at a subsequent date, developed this idea of relativity and
showed that things are as they appear to each individual at the moment
they are perceived. He summarized his teaching in the aphorism: Man is
the measure of all things.
The Skeptics, 200 years later, developed the Protagorean theory of
relativity, and by a series of arguments attempted to prove that
perceptions change not only with the different species of animate
beings, but with many conditions and circumstances. It was also shown
that not only man's perceptions are subject to changes, but also his
opinions following from his perceptions. Another school taught that to
every opinion the opposite can be opposed with equally good reasons.