Biographical encyclopedia
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41 [63] TSAI LUN PTOLEMY
he wrote on many branches of applied science—on land surveying and military science, for instance. These books do not survive. In 97 the Emperor Nerva put him in charge of the water system of Rome. As a result, he published a two- volume work describing the Roman aqueducts, probably the most informa tive work we possess on ancient en gineering. He proudly pointed out the superiority of these useful aqueducts as compared with the useless engineering feats of the Egyptians and the Greeks. However, Roman engineering had al ready peaked and the long, slow decline was beginning, with a new period of ad vance not slated to begin for sixteen weary centuries. [63] TSAI LUN (tsy loon) Chinese inventor
China, about 50 Died: about 118 Tsai Lun was a eunuch; the only one, perhaps, who can claim a key position in the history of science. Only one deed is recorded of him in the ancient Chinese histories, but that one deed is enough, for in 105 he is sup posed to have invented the making of paper from such substances as tree bark, hemp, and rags. Slowly, in the centuries afterward, the secret of papermaking spread westward. It reached Baghdad by a .
. 800 and Europe after the Crusades. It was in time to serve as the material of which to make the flood of books pro duced by the printing press invented by Gutenberg [114], thirteen centuries after Tsai Lun’s time. No substance, in the nineteen centuries since Tsai Lun’s time, has come along to supplant paper. [64] PTOLEMY (tol'uh-mee; Latin name), CLAUDIUS PTOLEMAEUS Greek astronomer Born: Ptolemais Hermii (?), about 100 Died: about 170 Ptolemy may have been an Egyptian rather than a Greek. He was not a member of the royal family of the Ptole mies that ruled Egypt a half century be fore his birth but may have attained his name from his supposed birthplace. Some traditions place him at Alexandria over a forty-year period, others say that he died at the age of seventy-eight. As you see, nothing is known of his private life, even his nationality, that goes be yond conjecture. As in the case of Euclid [40], Ptolemy is not important for his own work, but rather for the grand synthesis he pro duced. He drew principally on the work of Hipparchus [50], but since virtually none of the latter’s writings survive, the sys tem of the universe that he obtained from Hipparchus is universally referred to now as the Ptolemaic system. (Some, in fact, go so far as to suppose that Ptolemy was little more than a copyist of Hipparchus. This is probably too ex treme, however.) In the Ptolemaic system, the earth is at the center of the universe and the vari ous planets revolve about it. The planets, in order of increasing distance from the earth, are the moon, Mercury, Venus, the sun, Mars, Jupiter, and Saturn. To account for their actual motions as seen in the sky, Hipparchus’ epicycles and ec centrics are used, and Ptolemy very likely added a few refinements of his own.
The Ptolemaic system could be used to predict the positions of the planets for some time into the future and with an accuracy that was good enough for rea sonable naked-eye observation. It was not until the time of Tycho Brahe [156], fourteen centuries later, that observa tions of the planets were made with sufficient accuracy to require a theory better than Ptolemy’s. In his book Ptolemy also included a star catalogue based on Hipparchus, listed forty-eight constellations to which he gave the names we still use today, and preserved and extended the work of Hipparchus on trigonometry. He even described instruments to be used in as 4 2
[65] GALEN
GALEN [65] tronomic observations. His book was called by the admiring generations that followed Megale mathematike syntaxis (“Great mathematical composition”). Sometimes they said Megiste (“Great est”) rather than Megale. After the fall of the Roman Empire, Ptolemy’s works survived among the Arabs, who adopted the Greek word and called the book “The Greatest” using their own al, meaning “the.” The book thus became the Almagest and has re mained so ever since. The Arabic ver sions of the book were finally translated into Latin in 1175, and dominated Euro pean astronomical thinking through the Renaissance. For instance, Ptolemy accepted Hip parchus’ correct estimate of the distance of the moon, and also Aristarchus’ [41] incorrect estimate of the distance of the sun. The latter estimate held the field till the time of Kepler [169]. He also treated astrology seriously, following Posei- donius [52] in this respect and this helped that pseudoscience gain a respect it did not deserve. Ptolemy wrote a book on optics in which he discussed the refraction of light and he also wrote a book on geography based on the marchings of the Roman le gions through the known world. He in cluded maps and painstakingly prepared tables of latitudes and longitudes. How ever, he made a serious error in accept ing Poseidonius’ rather than Eratosthe nes’ [48] estimate of the earth’s size. The geography was translated into Latin, thirteen centuries later, just in time to persuade Toscanelli [113] and, through him, Columbus [121] of the feasibility of a westward voyage from Europe to Asia. [65] GALEN (gayflen) Greek physician
in Turkey), about 130 Died: probably in Sicily, about 200
Galen’s father had been an architect. Tradition has it that Asklepios, the god of medicine, came to him in a dream and told him to make a physician of his son. He did. Galen spent his youth traveling about the eastern provinces of the Roman Em pire, receiving his education. He even visited the medical school at Alexandria. About 159 he was appointed physician to the gladiatorial school at Pergamum, which gave him ample opportunity for some rough and ready observations in human anatomy. In 161 he settled in Rome and spent most of his active life in that city, where for a time he was court physician under the emperor Marcus Aurelius. He was close, also, to two later emperors, Corn- modus and Septimius Severus. Galen’s best work was in anatomy. The dissection of human beings had fal len into disrepute and Galen’s work was confined to animals, including dogs, goats, pigs, and monkeys. What he saw, he described with great and meticulous detail, but of course not everything he saw was applicable to human anatomy. For instance, he carefully described a network of blood vessels under the brain, present in many animals but not in man, and assigned it an important role in his scheme of the functioning of the human body.
Nevertheless, he did particularly good work on muscles, identifying many for the first time. He noted they worked in teams. He also showed the importance of the spinal cord by cutting it at various levels (in animals) and noting the extent of the resulting paralysis. Galen developed an overall system of physiology that was based to a great ex tent on the three-fluid theory of Erasis- tratus [43]. Galen recognized that the fluid in the left half of the heart must get to the right half somehow and postulated the presence of tiny holes, too small to see, in the thick muscular wall separating the two halves. In this way he missed the true explanation of the circulation of the blood. On the other hand, he was the first to use the pulse as a diagnostic aid, and he described the flow of urine through the ureters to the bladder. He was a prolific writer who engaged in polemics with other physicians,
[6 6 ] DIOPHANTUS ZOSIMUS
thought little of Hippocrates [22], and showed a rather unattractive side to his character in his arrogance, disputa tiousness, and pompous self-esteem. He was violently anti-atomist and this helped keep the views of Democritus [20] submerged until modern times. Galen lived at a time when Chris tianity was rising in power, and although he was not himself a Christian he de veloped a form of monotheism. He believed, somewhat as Pliny [61] did, that everything in the universe was made by God for a particular purpose. This search for design and purpose in the universe and particularly in the human body made his works popular with Christians and ensured the survival of many of his books through the Middle Ages. Galen’s works, then, were the ultimate medical authority for Europeans until the time of Vesalius [146] in anatomy and Harvey [174] in physiology. [66] DIOPHANTUS (dy-oh-fan'tus) Greek mathematician
The great glory of Greek mathematics was geometry and its great shortcoming was the lack of algebra. It was only in the late twilight of ancient Greek science that a mathematician erased that short coming. Nothing is known of Diophantus but his work, not even the century in which he lived. The year of birth given here, 210, is one guess. Others have placed it as early as 50. One problem associated with him requires that his age be de duced from data given. If that is autobi ographically accurate, he may have lived to be eighty-four. Diophantus solved problems by means of what we would now call algebraic equations, working out a symbolism of his own. His works were preserved by the Arabs and were translated into Latin in the sixteenth century, when they served as inspiration for the great al gebraic advances that began at that time. He is best known for his work with equations for which solutions in terms of integers are required. Sometimes the equation is indeterminate, that is, has no single set of solutions. It has, instead, more than one or even an infinite num ber. These are still called Diophantine equations. Diophantus was the first Greek to treat fractions as numbers.
Greek alchemist Bom: Panopolis (modern Akhmim), Egypt, about 250 Died: date unknown While the Greeks excelled in mathe matics and in abstract schemes of the universe, the Egyptians dealt in a practi cal way with materials. This interest in what we would today call chemistry arose, perhaps, out of their efforts to preserve the human body after the death through mummification. After the time of Alexander the Great, Egyptian practice fused with Greek theory to form the science of “khemia.” (Some people find the source of this word in khem, the Egyptian word for land. It means “black” and refers to the fertile black soil watered by the Nile floods, as compared with the tawny soil of the desert areas beyond.) The Arabs eventually inherited this science and placed al (“the”) before the name, so that it became “alchemy.” Very little of the original Greek or Egyptian writings on alchemy survive, but about three hundred, the entire range of alchemical knowledge, were summarized by Zosimus (concerning whose personal life nothing is known) in an encyclopedia made up of twenty-eight books. These books are a riot of mysticism. This is perhaps understandable. If al chemy was indeed born of Egyptian mummification procedures, then it began in close association with religion. It was a form of knowledge that would natu rally be considered sacred and of pecu liar interest to the priestly class. It would
[6 8 ] PAPPUS
PROCLUS [70] become habitual to discuss it in a jargon that would exclude the uninitiated. It is possible to find, among the ob scure references of Zosimus, passages that indicate he may have known of ar senic. Also, he seems to have described the formation of lead acetate and to have known of its sweet taste. (It is called “sugar of lead” even today.) The Greek theories of the four ele ments led alchemists to think that it was possible to rearrange the elements in a base metal such as lead to form the noble metal gold. This is transmutation. The will-o’-the-wisp of transmutation combined with the tradition of mysticism and obscure symbolism in alchemical writings held back the development of chemistry until the time of Lavoisier [334], who, fifteen centuries after Zo simus, finally completed the breaking of the spell. [68] PAPPUS (pap'us) Greek mathematician
Pappus, like Zosimus [67] and Dio- phantus [66], brought up the rear guard of Greek science. Like Zosimus, he was primarily an encyclopedist, summarizing in eight rather masterly books (of which major parts of all but the first survive) all of Greek mathematics. He contributed little himself but his collection is of first importance, never theless, for it contains almost all we know of Greek mathematicians. Pappus also commented in detail on Ptolemy’s astronomical system and helped keep it popular for the next millennium and a half.
[69] HYPATIA (hy-pay'shee-uh) Greek philosopher Born: Alexandria, about 370 Died: Alexandria, 415 Hypatia, the daughter of Theon, who was the last recorded member of the great Museum at Alexandria, is remark able as the only noted woman scholar of ancient times. This, combined with re ports as to her beauty and virtue and the skill and popularity of her lectures, has led to her idealization in later times. Like her father, she contributed nothing original to science but produced useful commentaries on a number of earlier scholars such as Ptolemy [64] and Dio- phantus [66]. She was a pagan, and, although Chris tian bishops were among her pupils, she was the subject of violent antagonism on the part of zealots. In the end she was brutally murdered. Her story was greatly romanticized by Charles Kingsley, in his novel Hypatia, published in 1853. [70] PROCLUS (prohldus) Greek mathematician
modem Istanbul, Turkey), 410 Died: Athens, April 17, 485 Proclus, the son of a lawyer, was vir tually the last pagan scientist of any con sequence. He was a devotee of Neopla tonism, a system of philosophy that stemmed from the work of Plotinus, a Roman philosopher. Plotinus, two cen turies before, had modified the system of Plato, adding mysticism in order to make it more capable of competing with the Salvationist Eastern religions then begin ning to dominate the Roman Empire. In this, Plotinus failed, but Neo-Platonist el ements entered into the thinking of Christianity, which was the ultimate vic tor in the battle of ideas. By Proclus’ time it had become dan gerous (though not yet fatal) to be a pagan. Proclus, who was the last neo Platonist of importance and who taught at the Academy in the last century of its existence and served as its head eventu ally, found that out. About 450 he was driven into a year’s exile from Athens. Among his writings Proclus included commentaries on Ptolemy [64] and Eu clid [40] and it is there that his impor tance to the history of science lies. The flame of science had dimmed to such a feeble flicker that any commentary, how 45 [7 1 ] BOETHIUS
BRAHMAGUPTA [73] ever primitive, was important, for it added one more book that might be seen and that might survive. [71] BOETHIUS, Anicius Manlius Sev erinus (boh-ee'thee-us) Roman philosopher
Italy, 524 Boethius, who represented the last spark of the old Greco-Roman world, came of a noble Roman family. One of that family was Olybrius who, for a few months in 472-73, reigned as puppet emperor of Rome. In Boethius’ time, no emperor reigned at Rome, for the last had been deposed in 476, the date usu ally taken as the fall of Rome. Boethius, however, was befriended by Theodoric, ruler of the Ostrogoths, and the supreme power in Italy and the lands immediately surrounding. It was a fatal friendship, as it turned out, for Boethius, who was given high office and who, in 522, had the pleasure of seeing his two sons simultaneously raised to the honor able office of consul, was tactlessly vocal concerning the abuses visited by the Os- trogothic overlords upon the Roman pop ulace. Eventually his attitude was unjustly translated, by an increasingly suspicious Theodoric, into treasonable correspondence with the Eastern em peror at Constantinople. Boethius was imprisoned, tortured, and finally exe cuted without trial. Boethius’ chief work (written in prison) was a philosophic treatise, On
great work, rather pagan in its discussion of virtue and free will, although Boethius is considered to have been a Christian. He was the last Roman writer who un derstood Greek, and his service to sci ence lies in his having prepared trans lations of and commentaries on Aristotle [29] and summaries on various scientific subjects. His works were the only source from which the Europeans of the early Middle Ages could draw for information on Greek science until Arabic works were translated into Latin about six cen turies after the time of Boethius. [72] ISIDORE OF SEVILLE Spanish scholar
Isidore was a great controversialist, defending Christianity against the Jews, and Catholicism against the heresy of Arianism. In 609 he was made Arch bishop of Seville. Between 622 and 633 Isidore published an encyclopedia in which, like Bede [75] a few decades later, he salvaged all he could of the learning of the Greeks, borrowing, again like Bede, from Pliny in particular. This book, called Etymologies in English, was very influential in early medieval times. It was so popular that a thousand medi eval manuscripts of the book still sur vive.
Isidore accepted the validity of astrol ogy and this contributed to its accep tance in medieval Europe, even though Biblical verses could be quoted against it. He also dealt with the mystic significance of numbers after the fashion of Pythagoras [7]. His work, on the whole, tended to darken the intellectual world rather than enlighten it; but like Pliny he kept alive a sense of wonder, and that is important, too. [73] BRAHMAGUPTA (brah'muh- goop'tuh) Hindu astronomer and mathe matician
When Greek learning was spreading eastward, during and after the time of the Arabic conquest of the Near East, it penetrated as far as the Indian subcon tinent. The men of science who arose there had little influence on subsequent developments in the West but Brah magupta, as perhaps the best among them, ought to be mentioned. He worked at Ujjain, in west-central India, which, for several centuries before and after him, was the center of Hindu science. Brahmagupta’s astronomy was summarized in a book written in 628 and in it he denied the rotation of the Download 17.33 Mb. Do'stlaringiz bilan baham: 
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