A History of Science, vol 1, Henry Smith Williams [read out loud books TXT] 📗

the cosmos, the origin and development of animals and man, and the nature of matter itself. Nowadays, so enormously involved has become the mass of mere facts regarding each of these departments of knowledge that no one man has the temerity to attempt to master them all. But it was different in those days of beginnings. Then the methods of observation were still crude, and it was quite the custom for a thinker of forceful personality to find an eager following among disciples who never thought of putting his theories to the test of experiment. The great lesson that true science in the last resort depends upon observation and measurement, upon compass and balance, had not yet been learned, though here and there a thinker like Anaxagoras had gained an inkling of it.

For the moment, indeed, there in Attica, which was now, thanks to that outburst of Periclean culture, the centre of the world’s civilization, the trend of thought was to take quite another direction. The very year which saw the birth of Democritus at Abdera, and of Hippocrates, marked also the birth, at Athens, of another remarkable man, whose influence it would scarcely be possible to overestimate. This man was Socrates. The main facts of his history are familiar to every one. It will be recalled that Socrates spent his entire life in Athens, mingling everywhere with the populace; haranguing, so the tradition goes, every one who would listen; inculcating moral lessons, and finally incurring the disapprobation of at least a voting majority of his fellow-citizens. He gathered about him a company of remarkable men with Plato at their head, but this could not save him from the disapprobation of the multitudes, at whose hands he suffered death, legally administered after a public trial. The facts at command as to certain customs of the Greeks at this period make it possible to raise a question as to whether the alleged “corruption of youth,” with which Socrates was charged, may not have had a different implication from what posterity has preferred to ascribe to it. But this thought, almost shocking to the modern mind and seeming altogether sacrilegious to most students of Greek philosophy, need not here detain us; neither have we much concern in the present connection with any part of the teaching of the martyred philosopher. For the historian of metaphysics, Socrates marks an epoch, but for the historian of science he is a much less consequential figure.

Similarly regarding Plato, the aristocratic Athenian who sat at the feet of Socrates, and through whose writings the teachings of the master found widest currency. Some students of philosophy find in Plato “the greatest thinker and writer of all time.”[1]

The student of science must recognize in him a thinker whose point of view was essentially non-scientific; one who tended always to reason from the general to the particular rather than from the particular to the general. Plato’s writings covered almost the entire field of thought, and his ideas were presented with such literary charm that successive generations of readers turned to them with unflagging interest, and gave them wide currency through copies that finally preserved them to our own time. Thus we are not obliged in his case, as we are in the case of every other Greek philosopher, to estimate his teachings largely from hearsay evidence. Plato himself speaks to us directly. It is true, the literary form which he always adopted, namely, the dialogue, does not give quite the same certainty as to when he is expressing his own opinions that a more direct narrative would have given; yet, in the main, there is little doubt as to the tenor of his own opinions—except, indeed, such doubt as always attaches to the philosophical reasoning of the abstract thinker.

What is chiefly significant from our present standpoint is that the great ethical teacher had no significant message to give the world regarding the physical sciences. He apparently had no sharply defined opinions as to the mechanism of the universe; no clear conception as to the origin or development of organic beings; no tangible ideas as to the problems of physics; no favorite dreams as to the nature of matter. Virtually his back was turned on this entire field of thought. He was under the sway of those innate ideas which, as we have urged, were among the earliest inductions of science. But he never for a moment suspected such an origin for these ideas. He supposed his conceptions of being, his standards of ethics, to lie back of all experience; for him they were the most fundamental and most dependable of facts. He criticised Anaxagoras for having tended to deduce general laws from observation. As we moderns see it, such criticism is the highest possible praise. It is a criticism that marks the distinction between the scientist who is also a philosopher and the philosopher who has but a vague notion of physical science. Plato seemed, indeed, to realize the value of scientific investigation; he referred to the astronomical studies of the Egyptians and Chaldeans, and spoke hopefully of the results that might accrue were such studies to be taken up by that Greek mind which, as he justly conceived, had the power to vitalize and enrich all that it touched. But he told here of what he would have others do, not of what he himself thought of doing.

His voice was prophetic, but it stimulated no worker of his own time.

Plato himself had travelled widely. It is a familiar legend that he lived for years in Egypt, endeavoring there to penetrate the mysteries of Egyptian science. It is said even that the rudiments of geometry which he acquired there influenced all his later teachings. But be that as it may, the historian of science must recognize in the founder of the Academy a moral teacher and metaphysical dreamer and sociologist, but not, in the modern acceptance of the term, a scientist. Those wider phases of biological science which find their expression in metaphysics, in ethics, in political economy, lie without our present scope; and for the development of those subjects with which we are more directly concerned, Plato, like his master, has a negative significance.

ARISTOTLE (384-322 B.C.)

When we pass to that third great Athenian teacher, Aristotle, the case is far different. Here was a man whose name was to be received as almost a synonym for Greek science for more than a thousand years after his death. All through the Middle Ages his writings were to be accepted as virtually the last word regarding the problems of nature. We shall see that his followers actually preferred his mandate to the testimony of their own senses. We shall see, further, that modern science progressed somewhat in proportion as it overthrew the Aristotelian dogmas. But the traditions of seventeen or eighteen centuries are not easily set aside, and it is perhaps not too much to say that the name of Aristotle stands, even in our own time, as vaguely representative in the popular mind of all that was highest and best in the science of antiquity. Yet, perhaps, it would not be going too far to assert that something like a reversal of this judgment would be nearer the truth. Aristotle did, indeed, bring together a great mass of facts regarding animals in his work on natural history, which, being preserved, has been deemed to entitle its author to be called the “father of zoology.” But there is no reason to suppose that any considerable portion of this work contained matter that was novel, or recorded observations that were original with Aristotle; and the classifications there outlined are at best but a vague foreshadowing of the elaboration of the science. Such as it is, however, the natural history stands to the credit of the Stagirite. He must be credited, too, with a clear enunciation of one most important scientific doctrine—namely, the doctrine of the spherical figure of the earth. We have already seen that this theory originated with the Pythagorean philosophers out in Italy. We have seen, too, that the doctrine had not made its way in Attica in the time of Anaxagoras. But in the intervening century it had gained wide currency, else so essentially conservative a thinker as Aristotle would scarcely have accepted it. He did accept it, however, and gave the doctrine clearest and most precise expression. Here are his words:[2]

“As to the figure of the earth it must necessarily be spherical…. If it were not so, the eclipses of the moon would not have such sections as they have. For in the configurations in the course of a month the deficient part takes all different shapes; it is straight, and concave, and convex; but in eclipses it always has the line of divisions convex; wherefore, since the moon is eclipsed in consequence of the interposition of the earth, the periphery of the earth must be the cause of this by having a spherical form. And again, from the appearance of the stars it is clear, not only that the earth is round, but that its size is not very large; for when we make a small removal to the south or the north, the circle of the horizon becomes palpably different, so that the stars overhead undergo a great change, and are not the same to those that travel in the north and to the south. For some stars are seen in Egypt or at Cyprus, but are not seen in the countries to the north of these; and the stars that in the north are visible while they make a complete circuit, there undergo a setting. So that from this it is manifest, not only that the form of the earth is round, but also that it is a part of a not very large sphere; for otherwise the difference would not be so obvious to persons making so small a change of place. Wherefore we may judge that those persons who connect the region in the neighborhood of the pillars of Hercules with that towards India, and who assert that in this way the sea is one, do not assert things very improbable. They confirm this conjecture moreover by the elephants, which are said to be of the same species towards each extreme; as if this circumstance was a consequence of the conjunction of the extremes. The mathematicians who try to calculate the measure of the circumference, make it amount to four hundred thousand stadia; whence we collect that the earth is not only spherical, but is not large compared with the magnitude of the other stars.”

But in giving full meed of praise to Aristotle for the promulgation of this doctrine of the sphericity of the earth, it must unfortunately be added that the conservative philosopher paused without taking one other important step. He could not accept, but, on the contrary, he expressly repudiated, the doctrine of the earth’s motion. We have seen that this idea also was a part of the Pythagorean doctrine, and we shall have occasion to dwell more at length on this point in a succeeding chapter. It has even been contended by some critics that it was the adverse conviction of the Peripatetic philosopher which, more than any other single influence, tended to retard the progress of the true doctrine regarding the mechanism of the heavens.

Aristotle accepted the sphericity of the earth, and that doctrine became a commonplace of scientific knowledge, and so continued throughout classical antiquity. But Aristotle rejected the doctrine of the earth’s motion, and that doctrine, though promulgated actively by a few contemporaries and immediate successors of the Stagirite, was then doomed to sink out of view for more than a thousand years. If it be a correct assumption that the influence of Aristotle was, in a large measure, responsible for this result, then we shall perhaps not be far astray in assuming that the great founder