Aristotle was born in Stagira (in northern Greece), 384 B.C. He died in Chalcis (on the Aegean island of Euboea, now Ewoia), 322 B.C. Inland from Stagira was the semi-Greek kingdom of Macedon, with which Aristotle's family was closely connected. Aristotle's father, for instance, had been court physician to the Macedonian king Amyntas II. Aristotle lost both parents while a child and was brought up by a friend of the family. He is supposed to have spoken with a lisp and to have been something of a dandy.
At the age of seventeen Aristotle traveled to Athens for a college education and after Plato returned from Syracuse, the young man joined Plato's Academy, where he studied assiduously. Eventually he was to become by far the most renowned of all the pupils of Plato. Plato called him "the intelligence of the school."
When Plato died in 347 B.C., Aristotle left the school. The reason he gave was that he disapproved of the growing emphasis on mathematics and theory in the Academy and the continuing decline in natural philosophy. However, it is possible that he may have been displeased that Plato, on his deathbed, designated his nephew, an undistinguished person, as his successor, passing over the merits of Aristotle. It is also true that Athens and Macedon were enemies at the time and Aristotle may have felt uneasily conscious of being considered pro-Macedonian.
In any case Aristotle found it expedient to set out upon a journey that carried him to various parts of the Greek world, particularly to Asia Minor. While there he married and engaged in the study of biology and natural history, always his chief love.
In 342 B.C. he was called to Macedon. The son of Amyntas II had succeeded to the throne of Macedon as Philip II while Aristotle was at the Academy, and now the king wanted the son of his father's physician back at court. The purpose was to install him as tutor for his fourteen-year-old son, Alexander. Aristotle held this position for several years. Since Alexander was to become Alexander the Great, the conqueror of Persia, we have the spectacle of the greatest soldier of ancient times being tutored by the greatest thinker.
In 336 B.C. Philip II was assassinated and his son succeeded as Alexander III. Alexander had no further time for education so Aristotle left Macedon the next year and went back to Athens while Alexander went on to invade the Persian Empire in a great conquering campaign. Aristotle's nephew, Callisthenes, accompanied Alexander, but Aristotle's influence over his erstwhile pupil was not very great for in 327 B.C. Callisthenes was executed by the increasingly megalomaniac monarch.
Meanwhile, in Athens, Aristotle founded a school of his own, the Lyceum, so called because Aristotle lectured in a hall near the temple to Apollo Lykaios (Apollo, the Wolf-God). It was also called the "peripatetic school" (walk about) because Aristotle, at least on occasion, lectured to students while walking in the school's garden. He also built up a collection of manuscripts a very early example of a "university library." It was this which eventually served as the kernel for the great Library at Alexandria.
The school continued under Aristotle's directorship quite successfully, emphasizing natural philosophy. In 323 B.C., however, the news arrived of the death of Alexander the Great in Babylon. Since Aristotle was well known to have been Alexander's tutor, he feared that an anti Macedonian reaction in Athens might lead to trouble. And, indeed, the accusation of "impiety" was raised. Aristotle had no mind to suffer the fate of Socrates. Saying he would not allow Athens to "sin twice against philosophy" he prudently retired to Chalcis, his mother's hometown, and died there the next year.
Aristotle's lectures were collected into nearly 150 volumes and represent almost a one-man encyclopedia of the knowledge of the times, much of it representing the original thought and observation of Aristotle himself. Nor was it confined entirely to science, for Aristotle dealt with politics, literary criticism, and ethics. Altogether, of the volumes attributed to him, some fifty have survived (not all of which are certainly authentic), a survival record second only to that of Plato. This survival came about through a fortunate chance. Many of his manuscripts were found in a pit in Asia Minor about 80 B.C. by men in the army of the Roman general Sulla. They were then brought to Rome and recopied.
The one field for which Aristotle is not noted is mathematics, but even here he may be credited with a glancing blow, for he is the virtual founder of the systematic study of logic, which is allied to mathematics. He developed, in great and satisfying detail, the art of reasoning from statement to necessary conclusion and thereby demonstrating the validity of a line of thought. His system stood without major change until the nineteenth-century development of symbolic logic by Boole, which converted logic in to a branch of mathematics in form as well as spirit.
Aristotle's most successful scientific writings were those on biology. He was a careful and meticulous observer who fascinated by the task of classifying animal species and arranging them into hierarchies. He dealt with over five hundred animal species in this way and dissected nearly fifty of them. His mode of classification was reasonable and, in some cases, strikingly modern. He was particularly interested in sea life and observed that the dolphin brought forth its young alive and nourished the fetus by means of a special organ called a placenta. No fish did this, but all mammals did, so Aristotle classed the dolphin with the beasts of the field rather than with the fish of the sea. His successors did not follow his lead, however, and it took two thousand years for biologists to catch up to Aristotle in this respect. It was J. Muller who finally confirmed Aristotle in this respect. Aristotle also studied viviparous sharks, those that bear live young -- but without a mammalian placenta. He also noted the odd ability of the torpedo fish to stun its prey though, of course, he knew nothing of the electric shock with which it managed it. He was also wrong on occasion, as when he denied sexuality in plants. Nineteen centuries were to pass before Alpini was to correct this particular error.
His formation of a hierarchy of living things led him irresistibly toward the idea that animals represented a chain of progressive change, a sort of evolution. Other Greek philosophers groped similarly in this direction. However, barring any knowledge as to the physical mechanism whereby evolutionary changes could be brought about, such theories invariably became mystical. A rational theory of evolution had to await Darwin, 2200 years after the time of Aristotle.
Aristotle studied the developing embryo of the chick and the complex stomach of cattle. He decided that no animal had both tusks and horns, and that no single hoofed animal had horns. But his intuition sometimes led him astray. He believed the heart was the center of life and considered the brain merely a cooling organ for the blood.
In physics Aristotle was far less successful than in biology, perhaps because he was too Platonic. He accepted the heavenly spheres of Eudoxus and Callippus and even added further to them, reaching a total of 54. He seemed to think of the spheres as having an actual physical existence whereas Eudoxus probably thought of them as imaginary aids to calculation, as we consider the lines of latitude and longitude we draw on a map. Aristotle also accepted the four elements of Empedocles but restricted them to Earth itself. He suggested a fifth element "aether," of which all the heavens were composed. (We still use phrases such as "ethereal heights" today.)
This line of reasoning led him to agree with the Pythagoreans that Earth and heaven were subjected to two different sets of natural law. On Earth all things were changeable and corrupt, while in the heavens all was permanent and unchanging. On Earth the four elements each had its own place, and motion was an attempt to reach that place. Earth was in the center, water above it, air above that, and fire highest of all the earthly substances. Therefore an object composed largely of earth, such as a rock, would, if suspended in air, fall downward, while bubbles of air trapped under water would move upward. Again rain fell, but fire rose.
It also seemed to Aristotle that the heavier an object was, the more eagerly it would strive to achieve its proper place since the heaviness was the manifestation of its eagerness to return. Hence a heavier object would fall more rapidly than a lighter one. Nineteen centuries later, a reconsideration of this problem by Galileo was to lead to momentous consequences. The motion of heavenly objects, on the other hand, was no attempt to get anywhere. It was a steady, permanent motion, even and circular.
Aristotle, apparently, was not an experimentalist for all that he was a close observer. He observed that rocks fell more quickly than feathers, but he made no attempt to arrange an observation of the falling of rocks of graded weight. Furthermore, neither he nor any other ancient scholar properly appreciated the importance of precise, quantitative measurement. This was not mere perversity on their part, for the state of instrumentation was rudimentary indeed in ancient times and there were few clear methods of making accurate measurements. In particular, they could not measure small intervals of time accurately, a deficiency that was to remain for two thousand years until the time of Huygens.
Aristotle rejected Democritus' atomism, dooming that concept through ancient and medieval times. On the other hand, he accepted the Pythagorean notion of the roundness of Earth, presenting his reasoning in a fashion that remains valid today. The most telling argument was that as one travels north, new stars appear at the northern horizon while old ones disappear at the southern. If Earth were flat, all stars would be equally visible from all points on its surface. It was Aristotle's championing of this view that kept it alive through the darkest days that were to follow.
Aristotle's system of philosophy was never as influential in ancient times as Plato's. Indeed, Aristotle's works may not have been published for some centuries after his death. After the fall of Rome, his work was largely lost to Europe (only Organon, his work on logic, was saved) while Plato's works were, for the most part, retained. However, Aristotle's books survived among the Arabs, who valued them highly.
Christian Europe regained Aristotle from the Arabs, translating his books into Latin in the twelfth and thirteenth centuries. From that time Aristotle replaced Plato as the Philosopher. His views came to be regarded as possessing an almost divine authority, so that if Aristotle said it was so, it was so. By a queer fatality, it almost seemed as though his statements were most accepted when they were most incorrect.
This cannot be blamed on Aristotle, who was himself no believer in blind obedience to authority. Nevertheless, following the era of over-adulation, he became the very symbol of wrongness, and when the Scientific Revolution took place in the sixteenth and seventeenth centuries, its first victories involved the overthrow of Aristotelian physics. In the centuries since, Aristotle has, as a consequence, too often been viewed as an enemy of science, whereas actually he was one of the truly great scientists of all time and even his wrongness was rational. No man should be blamed for the stubborn orthodoxy of those who many centuries later insist they speak in his name.
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