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21 [32] CALLIPPUS DIOCLES [34] Theophrastus came to Athens at an early age to study under Plato [24]. Aris totle [29] first met Theophrastus on Lesbos, during the period after Plato’s death, and a lifelong friendship ensued. In fact, Theophrastus (“divine speech”) is really a nickname bestowed upon the man by Aristotle because of the latter’s delight in his conversation. His real name was Tyrtamus. Theophrastus conducted the Lyceum after Aristotle’s retirement and served as guardian of his old teacher’s children. He inherited Aristotle’s library and re mained in charge of the school until his own death thirty-five years later. The school was at its peak of prosperity under him and is supposed to have had as many as two thousand students. Theophrastus carried on the Aris totelian tradition of biology, concen trating chiefly on the plant world and describing over five hundred and fifty species, some from as far away as India, for the conquests of Alexander the Great had opened wider horizons to Greek science. Theophrastus is usually considered the founder of botany, as Aristotle was the founder of zoology. Two botanical works are all that have survived of some two hundred scientific volumes he produced, one of which was a general history of science that would have been priceless if but one copy had survived. As it is, he is best known for no scientific work at all, however, but for a delightful series of character portraits that bear the mark of universality. The human “types” satirized by Theophrastus are easily recognized today. [32] CALLIPPUS (kuh-lip'us) Greek astronomer Born: Cyzicus, about 370 b . c .
Callippus, having studied under Eu doxus [27], improved on his master. His observations of planetary movements showed him that the spheres of Eudoxus, even though they numbered twenty-six in all, did not exactly account for reality no matter how their movements were adjusted. He added eight more spheres, making thirty-four in all. He also measured the length of the seasons accurately and obtained a mea sure of the year that was closer to the true value than was that of Oenopides [18].
[33] DICAEARCHUS (dy-see-ahrikus) Greek geographer Born: Messina, Sicily, about 355 B.C.
Died: ab o u t 285 b
c . As a young man Dicaearchus went to Athens, studying at the Lyceum under Aristotle [29] and becoming a close friend of Theophrastus [31]. Interested mostly in moral philosophy he never theless wrote a history of Greece and a geography in which he described the world in words and maps, being the first to consider such a map as part of a sphere. He estimated the heights of Greek mountains and showed they did not upset the notion of the sphericity of the earth by arguing that their height was very small compared to the width of the terrestrial sphere. He had the advantage of being able to use the descriptions brought back by the far-ranging officers of Alexander the Great. Dicaearchus’ most notable contri bution was that of being the first to draw a line of latitude from east to west across his maps, this marking the fact that all points on that line saw the noonday sun (on any given day) at an equal angle from the zenith. [34] DIOCLES (dy'uh-kleez) Greek physician
350
b . c . Died: date unknown Diodes, the son of a physician, was held in great esteem by the ancients as second only to Hippocrates [22] himself. He studied at the Lyceum under Aris totle [29], He may have been the first to assem
[35] EPICURUS KIDDINU [37] ble the writings of the Hippocratic school, and he made use of them in his own works, of which fragments survive. He is thought to have been the first per son to write a book on anatomy and the first to use the word itself to describe the study. He became prominent enough to treat some of the Macedonian princes and generals of the time of Alexander the Great. He seems also to have been the first Greek to write a manual on how to rec ognize different plants, and on how they might be used nutritionally and medi cally. This book served as the basic au thority on pharmacy until it was re placed by that of Dioscorides [59] nearly four centuries later. [35] EPICURUS (ep-ih-kyoo'rus) Greek philosopher
b . c .
b .
. Epicurus was the son of an Athenian schoolmaster and, after teaching in vari ous places in the Greek world, he settled in Athens in 306 b . c . There he founded an enormously popular school and es tablished the philosophy known as Epi cureanism. This maintained an unbroken tradition for seven centuries until the tide of Christianity in the late Roman Empire washed out all the pagan philos ophies. His school was the first to admit women students, which both shocked and titillated the scholarly world of the time.
Epicurus’ philosophy was mechanistic and found pleasure the chief human good. Epicurus himself held that the highest pleasure consisted of living mod erately and behaving kindly and in re moving the fear of the gods and of death. His later followers were more self-indulgent in their definition of plea sure and Epicureanism is nowadays unjustly used as a synonym for hedo nism. Epicurus may have been the stu dent of Nausiphanes who was himself a student of Democritus [20]. In any case, Epicurus adopted the atoms of Democ ritus as a satisfactorily mechanistic ex planation of the universe. Although of his voluminous writings (consisting, supposedly, of three hun dred treatises), practically nothing sur vives, they lasted long enough to convert the Roman Lucretius [53] some two and a half centuries later, and, in turn, Lu cretius’ writings lasted into modern times. Democritus’ atoms, though voted down by philosophers, were never wholly forgotten. Epicureanism, as a philosophy, en dured till nearly the end of the Roman Empire, but then perished with the rise of Christianity. [36] PRAXAGORAS (prak-sag'oh-ras) Greek physician Born: Cos, about 340 b . c .
Praxagoras, the son and grandson of physicians, was supposed to have been the teacher of Herophilus [42] and to have been a strong defender of the hu moral theory of Hippocrates [22]. Praxagoras distinguished between veins and arteries, recognizing that there were two different kinds of blood vessels, though some attribute this discovery to Alcmaeon [11]. The arteries, however, he thought carried air (they are usually empty in corpses) and the name of these vessels is derived from that belief. He thought moreover they tapered into very fine vessels (which they do) that led into the nerves (which they do not). He also noted the physical connection between the brain and spinal cord but thought the heart was the seat of the in tellect
[37] KIDDINU Babylonian astronomer Born: Babylonia, about 340 b . c .
It is certain that Babylonian astron omy was flourishing at a time when Greek astronomy was merely in its be ginnings. If the Babylonians did not, to our knowledge, work out the intricate (and often terribly mistaken) theories of the Greeks, they at least had centuries of
[38] STRATO PYTHEAS [39] careful observations to their credit. Their names and individual accomplishments are shadowy indeed, however, so that they are unjustly neglected in a bio graphical work such as this. There is mention of Kiddinu in Strabo [56] and Pliny [61], where he is called Kidenas or Cidenas. He was the head of the astronomical school at the Babylo nian city of Sippar and worked out the precession of the equinoxes, paving the way for Hipparchus’ [50] more accurate work.
He also devised, apparently, compli cated methods of expressing the irregular movement of the moon and other plane tary bodies, departing from the assump tion that they must move at constant velocities (something the Greeks insisted upon) and consequently getting close ap proximations of their actual movements. [38] STRATO (stray'toh) Greek physicist Born: Lampsacus, ab o u t 340 b
c .
b .
. Born in the city where two centuries earlier Anaxagoras [14] had died in exile and where Epicurus [35] had taught be fore moving on to Athens, Strato carried on in the tradition of Asia Minor. In youth, he studied at the Lyceum, then traveled to Alexandria, an Egyptian city founded by Alexander the Great. While there, he is supposed to have tutored the son of Ptolemy I, the Macedonian gen eral who had become Egypt’s king. He also helped establish Alexandria as a scientific center, a position it was to hold through the remainder of ancient times. Strato returned to Athens on the death of Theophrastus [31] to become third di rector of the Lyceum. Strato was a more advanced physicist than Aristotle [29], was favorable to Democritus’ [20] atomic theory, and apparently conducted ex periments. He was called Strato Physicus in ancient references. He described methods for forming a vacuum although he agreed with Aris totle that no vacuum existed in nature. He also agreed that heavier bodies fell faster than lighter ones, and he was the first to argue that, in falling, a body ac- celebrated; that is, moved more quickly with each successive unit of time. (It was the measurement of this acceleration by Galileo [166] that was to mark the birth of the new physics nineteen cen turies later.) Strato also seems to have understood the law of the lever, but he did not work it out as Archimedes [47] was to do later in the century. Where Aristotle had felt that sound traveled by a succession of impacts on air and that sound could not be conducted in the absence of air (he was right), Strato went further and seemed to be on the point of recognizing sound as a wave motion. After Strato’s death the Lyceum de clined. Primacy in philosophy remained in Athens with the Platonic Academy, but scientific endeavor was making its home increasingly in Alexandria. [39] PYTHEAS (pith'ee-us) Greek geographer and explorer Bom: Massalia (modern Mar seille, France), about 330 b .
. Died: date unknown Pytheas lived in a time of great outflowing of Greek energies. His con temporaries led Greek culture as far east as what are now the nations of Afghani stan and Pakistan. Pytheas, dwelling in Massalia, west ernmost of the Greek-colonized cities of the Mediterranean, turned in the other direction, not at the head of armies, but on board a ship. He sailed westward through the Pillars of Hercules (now the Strait of Gibraltar) and up the north western coast of Europe. His accounts, which have not survived directly but reach us through references in later writers, seem to show that he ex plored the island of Great Britain and then sailed northward to “Thule,” which was possibly Norway. There fog stopped the intrepid navigator and he turned back to explore northern Europe and penetrate the Baltic Sea as far as the Vistula.
Pytheas’ accounts, in the main truth ful, as nearly as we can tell, were disbe 24 [ 40 ]
EUCLID [
] lieved by contemporaries, who were much readier to believe fantasies. Even Pliny [61] some centuries later, who rou tinely swallowed five or six new impossi bilities each morning before breakfast, balked at Pytheas’ tales and the geogra pher, Strabo [56] was particularly abu sive. A similar fate had befallen Hanno [12] two centuries before Pytheas and was to befall Marco Polo [105] fifteen centuries after Pytheas. Pytheas was a scientific geographer as well as an explorer. Following the teach ings of the contemporary Dicaearchus [33], he determined the latitude of his hometown, Massalia, by careful observa tions of the sun, and did so with praise worthy accuracy. He was also the first to point out that the North Star was not ex actly at the pole and that it therefore shifted position, making a small circle in the course of a day. He improved on Eudoxus [27] in this respect. His voyages beyond Gibraltar led him into the open ocean, where he could ob serve the tides, which in the land-locked Mediterranean were almost nonexistent. What was most amazing was that, being the first Greek to observe real tides, he also produced the correct explanation for them, attributing them to the influence of the moon. In this, however, he was even further ahead of his time, for it was to be two thousand years before this ex planation was accepted and then only when Newton [231] had managed to ex plain lunar attraction as part of a grand scheme of the universe. [40] EUCLID (yoo'klid) Greek mathematician
ab o u t 325 b
c .
Euclid, who may have studied at Plato’s [24] Academy in Athens, is an other who marks the passage of scientific pre-eminence from Athens to Alexandria. After the death of Alexander the Great, his generals snatched at portions of his empire, fighting among themselves blood ily and inconclusively for a generation. One general, Ptolemy, seized Egypt and established his capital at the new city of Alexandria. He founded a line of kings, all named Ptolemy, that lasted for two and a half centuries. (The last monarch of the line was the famous queen Cleo patra.) Ptolemy and his immediate successors were patrons of science and labored to establish Alexandria as the intellectual capital of the world. In this, they suc ceeded. They built a splendid library and a famous university called the Museum, because it was a kind of temple to the Muses, who were the patron goddesses of science and the fine arts. Among the earliest scholars to be attracted to the new establishment was Euclid. Euclid’s name is indissolubly linked to geometry, for he wrote a textbook (Ele ments) on the subject that has been stan dard, with some modifications, of course, ever since. It went through more than a thousand editions after the invention of printing and it was not so long ago that the phrase “I studied my Euclid” was synonymous with “I studied geometry.” Euclid is, therefore, the most successful textbook writer of all time. And yet, as a mathematician, Euclid’s fame is not due to his own research. Few of the theorems in his textbook are his own. What Euclid did, and what made him great, was to take all the knowledge accumulated in mathematics since the days of Thales [3] and codify the two and a half centuries of labor into a single work. In doing so, he evolved, as a start ing point, a series of axioms and postu lates that were admirable for their brev ity and elegance. He then arranged theorem after theorem in a manner so logical as almost to defy improvement. The only theorem that tradition defi nitely ascribes to Euclid himself is the proof he presented for the Pythagorean theorem. Although most of his great treatise dealt with geometry, it also took up ratio and proportion and what is now known as the theory of numbers. It was Euclid who proved that the number of primes is infinite. He also proved that the square root of two was irrational (the fact first discovered by Pythagoras [7] and his fol lowers) by a line of argument so neat that it has never been improved upon.
[41] ARISTARCHUS ARISTARCHUS [41] He made optics a part of geometry, too, by dealing with light rays as though they were straight lines. Of course Euclid does not include all of Greek mathematics, or even all of Greek geometry. Greek mathematics re mained vital for a considerable time after Euclid, and such men as Apol lonius [49] and Archimedes [47] added a great deal. Yet Euclid as an individual remains an impenetrable mystery. It is not known where or just when he was bom or when he died. The figure given here, 325 b . c . is a pure guess, but he did work at Alex andria during the reign of Ptolemy 1 (305-285 b .
.). About the only personal aspect of Euclid’s life that reaches us is his re ported remark to King Ptolemy when the latter, studying geometry, asked if Euclid couldn’t make his demonstrations a little easier to follow. Euclid said, un compromisingly, “There is no royal road to geometry.” There is also a doubtful legend that gives him a shrewish wife. For many centuries it was considered that there was something objectively and eternally true about the principles of mathematics and, in particular, about the axioms on which Euclid’s work was based: that the whole is equal to the sum of its parts, for instance, or that a straight line is the shortest distance be tween two points. It was only in the nineteenth century that it came to be re alized that axioms are merely agreed- upon statements rather than absolute truths. Mathematics was broadened by men such as Lobachevski [484] and Rie- mann [670], and non-Euclidean geome tries, on which the theories of Einstein [1064] came to be based, were devel oped.
[41] ARISTARCHUS (ar-is-tahrikus) Greek astronomer Born: Samos, about 310 b . c .
b .
. Virtually nothing is known about the personal life of Aristarchus except that he must have come to Alexandria, then the Mecca for scientists, in his youth and may have studied under Strato [38]. Enough is known about his work, how ever, to stamp him as the most original and, from the modern view, successful of the Greek astronomers. Aristarchus combined the Pythagorean view of the moving earth with the con tention of Heracleides [28] that some planets moved about the sun. Aris tarchus pointed out, about 260 b . c .,
that the motions of the heavenly bodies could easily be interpreted if it were assumed that all the planets, including the earth, revolved about the sun. Since the stars seemed motionless, except for the diur nal motion due to the rotating earth, they must be infinitely far away. Because of this view, Aristarchus has been known as the Copernicus of Antiq uity and, indeed, Copernicus [127] seems to have known of Aristarchus’ views, mentioning them in a passage he later eliminated, as though not wishing to compromise his own originality. Aristarchus’ heliocentric hypothesis was too revolutionary to be accepted by the scholars of his time and his book on the subject did not survive. His theory would be forgotten today but for the mention of it in the writings of Archi medes [47] and of Plutarch, the Greek historian. The age was sufficiently enlightened, however, to protect Aristarchus from the dangers that had befallen Anaxagoras [14] two and a half centuries earlier for much less radical views. Yet, at least one important philosopher of the time, Cleanthes the Stoic, accused him of im piety and believed he should be made to suffer for it. From Aristarchus’ own writings we know of work he did to determine the size and distance of the moon and sun. At the moment when the moon is ex actly half-illuminated, the earth, moon, and sun must occupy the apices of a right triangle. By geometry one can then determine the relative lengths of the sides of the triangle and determine the ratio of the distance of the sun from the earth (the hypotenuse of the triangle) to the distance of the moon from the earth (the short leg of the triangle). In theory this method is correct, but unfortunately Download 17.33 Mb. Do'stlaringiz bilan baham: 
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