Читать книгу An Introduction to the History of Science - Walter Libby - Страница 6

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If you consult encyclopedias and special works in reference to the early history of any one of the sciences,—astronomy, geology, geometry, physiology, logic, or political science, for example,—you will find strongly emphasized the part played by the Greeks in the development of organized knowledge. Great, indeed, as we shall see in the next chapter, are the contributions to the growth of science of this highly rational and speculative people. It must be conceded, also, that the influence on Western science of civilizations earlier than theirs has come to us, to a considerable extent at least, through the channels of Greek literature.

Nevertheless, if you seek the very origins of the sciences, you will inevitably be drawn to the banks of the Nile, and to the valleys of the Tigris and the Euphrates. Here, in Egypt, in Assyria and Babylonia, dwelt from very remote times nations whose genius was practical and religious rather than intellectual and theoretical, and whose mental life, therefore, was more akin to our own than was the highly evolved culture of the Greeks. Though more remote in time, the wisdom and practical knowledge of Thebes and Memphis, Nineveh and Babylon, are more readily comprehended by our minds than the difficult speculations of Athenian philosophy.

Much that we have inherited from the earliest civilizations is so familiar, so homely, that we simply accept it, much as we may light, or air, or water, without analysis, without inquiry as to its origin, and without full recognition of how indispensable it is. Why are there seven days in the week, and not eight? Why are there sixty minutes in the hour, and why are there not sixty hours in the day? These artificial divisions of time are accepted so unquestioningly that to ask a reason for them may, to an indolent mind, seem almost absurd. This acceptance of a week of seven days and of an hour of sixty minutes (almost as if they were natural divisions of time like day and night) is owing to a tradition that is Babylonian in its origin. From the Old Testament (which is one of the greatest factors in preserving the continuity of human culture, and the only ancient book which speaks with authority concerning Babylonian history) we learn that Abraham, the progenitor of the Hebrews, migrated to the west from southern Babylonia about twenty-three hundred years before Christ. Even in that remote age, however, the Babylonians had established those divisions of time which are familiar to us. The seven days of the week were closely associated in men's thinking with the heavenly bodies. In our modern languages they are named after the sun, the moon, Mars, Mercury, Jupiter, Venus, and Saturn, which from the remotest times were personified and worshiped. Thus we see that the usage of making seven days a unit of time depends on the religious belief and astronomical science of a very remote civilization. The usage is so completely established that by the majority it is simply taken for granted.

Another piece of commonplace knowledge—the cardinal points of the compass—may be accepted, likewise, without inquiry or without recognition of its importance. Unless thrown on your own resources in an unsettled country or on unknown waters, you may long fail to realize how indispensable to the practical conduct of life is the knowledge of east and west and north and south. In this matter, again, the records of ancient civilizations show the pains that were taken to fix these essentials of science. Modern excavations have demonstrated that the sides or the corners of the temples and palaces of Assyria and Babylonia were directed to the four cardinal points of the compass. In Egypt the pyramids, erected before 3000 B.C., were laid out with such strict regard to direction that the conjecture has been put forward that their main purpose was to establish, in a land of shifting sands, east and west and north and south. That conjecture seems extravagant; but the fact that the Phɶnicians studied astronomy merely because of its practical value in navigation, the early invention of the compass in China, the influence on discovery of the later improvements of the compass, make us realize the importance of the alleged purpose of the pyramids. Without fixed points, without something to go by, men, before they had acquired the elements of astronomy, were altogether at sea. As they advanced in knowledge they looked to the stars for guidance, especially to the pole star and the imperishable star-group of the northern heavens. The Egyptians even developed an apparatus for telling the time by reference to the stars—a star-clock similar in its purpose to the sundial. By the Egyptians, also, was carefully observed the season of the year at which certain stars and constellations were visible at dawn. This was of special importance in the case of Sirius, for its heliacal rising, that is, the period when it rose in conjunction with the sun, marked the coming of the Nile flood (so important in the lives of the inhabitants) and the beginning of a new year. Not unnaturally Sirius was an object of worship. One temple is said to have been so constructed as to face that part of the eastern horizon at which this star arose at the critical season of inundation. Of another temple we are told that only at sunset at the time of the summer solstice did the sun throw its rays throughout the edifice. The fact that astronomy in Egypt as in Babylonia, where the temples were observatories, was closely associated with religion confirms the view that this science was first cultivated because of its bearing on the practical needs of the people. The priests were the preservers of such wisdom as had been accumulated in the course of man's immemorial struggle with the forces of nature.

It is well known that geometry had its origin in the valley of the Nile, that it arose to meet a practical need, and that it was in the first place, as its name implies, a measurement of the earth—a crude surveying, employed in the restoration of boundaries obliterated by the annual inundations of the river. Egyptian geometry cared little for theory. It addressed itself to actual problems, such as determining the area of a square or triangular field from the length of the sides. To find the area of a circular field, or floor, or vessel, from the length of the diameter was rather beyond the science of 2000 B.C. This was, however, a practical problem which had to be solved, even if the solution were not perfect. The practice was to square the diameter reduced by one ninth.

In all the Egyptian mathematics of which we have record there is to be observed a similar practical bent. In the construction of a temple or a pyramid not merely was it necessary to have regard to the points of the compass, but care must be taken to have the sides at right angles. This required the intervention of specialists, expert "rope-fasteners," who laid off a triangle by means of a rope divided into three parts, of three, four, and five units. The Babylonians followed much the same practice in fixing a right angle. In addition they learned how to bisect and trisect the angle. Hence we see in their designs and ornaments the division of the circle into twelve parts, a division which does not appear in Egyptian ornamentation till after the incursion of Babylonian influence.

There is no need, however, to multiply examples; the tendency of all Egyptian mathematics was, as already stated, concerned with the practical solution of concrete problems—mensuration, the cubical contents of barns and granaries, the distribution of bread, the amounts of food required by men and animals in given numbers and for given periods of time, the proportions and the angle of elevation (about 52°) of a pyramid, etc. Moreover, they worked simple equations involving one unknown, and had a hieroglyph for a million (the drawing of a man overcome with wonder), and another for ten million.

The Rhind mathematical papyrus in the British Museum is the main source of our present knowledge of early Egyptian arithmetic, geometry, and of what might be called their trigonometry and algebra. It describes itself as "Instructions for arriving at the knowledge of all things, and of things obscure, and of all mysteries." It was copied by a priest about 1600 B.C.—the classical period of Egyptian culture—from a document seven hundred years older.

EARLIEST PICTURE KNOWN OF A SURGICAL OPERATION. EGYPT, 2500 B.C.

Medicine, which is almost certain to develop in the early history of a people in response to their urgent needs, has been justly called the foster-mother of many sciences. In the records of Egyptian medical practice can be traced the origin of chemistry, anatomy, physiology, and botany. Our most definite information concerning Egyptian medicine belongs to the same general period as the mathematical document to which we have just referred. It is true something is known of remoter times. The first physician of whom history has preserved the name, I-em-hetep (He-who-cometh-in-peace), lived about 4500 B.C. Recent researches have also brought to light, near Memphis, pictures, not later than 2500 B.C., of surgical operations. They were found sculptured on the doorposts at the entrance to the tomb of a high official of one of the Pharaohs. The patients, as shown in the accompanying illustration, are suffering pain, and, according to the inscription, one cries out, "Do this [and] let me go," and the other, "Don't hurt me so!" Our most satisfactory data in reference to Egyptian medicine are derived, however, from the Ebers papyrus. This document displays some little knowledge of the pulse in different parts of the body, of a relation between the heart and the other organs, and of the passage of the breath to the lungs (and heart). It contains a list of diseases. In the main it is a collection of prescriptions for the eyes, ears, stomach, to reduce tumors, effect purgation, etc. There is no evidence of a tendency to homeopathy, but mental healing seems to have been called into play by the use of numerous spells and incantations. Each prescription, as in medical practice to-day, contains as a rule several ingredients. Among the seven hundred recognized remedies are to be noted poppy, castor-oil, gentian, colchicum, squills, and many other familiar medicinal plants, as well as bicarbonate of soda, antimony, and salts of lead and copper. The fat of the lion, hippopotamus, crocodile, goose, serpent, and wild goat, in equal parts, served as a prescription for baldness. In the interests of his art the medical practitioner ransacked the resources of organic and inorganic nature. The Ebers papyrus shows that the Egyptians knew of the development of the beetle from the egg, of the blow-fly from the larva, and of the frog from the tadpole. Moreover, for precision in the use of medicaments weights of very small denominations were employed.

The Egyptian embalmers relied on the preservative properties of common salt, wine, aromatics, myrrh, cassia, etc. By the use of linen smeared with gum they excluded all putrefactive agencies. They understood the virtue of extreme dryness in the exercise of their antiseptic art. Some knowledge of anatomy was involved in the removal of the viscera, and much more in a particular method they followed in removing the brain.

In their various industries the Egyptians made use of gold, silver, bronze (which on analysis is found to consist of copper, tin, and a trace of lead, etc.), metallic iron and copper and their oxides, manganese, cobalt, alum, cinnabar, indigo, madder, brass, white lead, lampblack. There is clear evidence that they smelted iron ore as early as 3400 B.C. maintaining a blast by means of leather tread-bellows. They also contrived to temper the metal, and to make helmets, swords, lance-points, ploughs, tools, and other implements of iron. Besides metallurgy they practiced the arts of weaving, dyeing, distillation. They produced soap (from soda and oil), transparent and colored glass, enamel, and ceramics. They were skilled in the preparation of leather. They showed aptitude for painting, and for the other fine arts. They were expert builders, and possessed the engineering skill to erect obelisks weighing hundreds of tons. They cultivated numerous vegetables, grains, fruits, and flowers. They had many domestic animals. In seeking the satisfaction of their practical needs they laid the foundation of geometry, botany, chemistry (named, as some think, from the Egyptian Khem, the god of medicinal herbs), and other sciences. But their practical achievements far transcended their theoretical formulations. To all time they will be known as an artistic, noble, and religious people, who cherished their dead and would not allow that the good and beautiful and great should altogether pass away.

Excavations in Assyria and Babylonia, especially since 1843, have brought to our knowledge an ancient culture stretching back four or five thousand years before the beginning of the Christian era. The records of Assyria and Babylonia, like those of Egypt, are fragmentary and still in need of interpretation. Here again, however, it is the fundamental, the indispensable, the practical forms of knowledge that stand revealed rather than the theoretical, speculative, and purely intellectual.

By the Babylonian priests the heavens were made the object of expert observation as early as 3800 B.C. The length of the year, the length of the month, the coming of the seasons, the course of the sun in the heavens, the movements of the planets, the recurrence of eclipses, comets, and meteors, were studied with particular care. One motive was the need of a measurement of time, the same motive as underlies the common interest in the calendar and almanac. It was found that the year contained more than 365 days, the month (synodic) more than 29 days, 12 hours, and 44 minutes. The sun's apparent diameter was contained 720 times in the ecliptic, that is, in the apparent path of the sun through the heavens. Like the Egyptians, the Babylonians took special note of the stars and star-groups that were to be seen at dawn at different times of the year. These constellations, lying in the imaginary belt encircling the heavens on either side of the ecliptic, bore names corresponding to those we have adopted for the signs of the zodiac,—Balance, Ram, Bull, Twins, Scorpion, Archer, etc. The Babylonian astronomers also observed that the successive vernal (or autumnal) equinoxes follow each other at intervals of a few seconds less than a year.

A second motive that influenced the Babylonian priests in studying the movements of the heavenly bodies was the hope of foretelling events. The planets, seen to shift their positions with reference to the other heavenly bodies, were called messengers, or angels. The appearance of Mars, perhaps on account of its reddish color, was associated in their imaginations with war. Comets, meteors, and eclipses were considered as omens portending pestilence, national disaster, or the fate of kings. The fortunes of individuals could be predicted from a knowledge of the aspect of the heavens at the hour of their birth. This interest in astrology, or divination by means of the stars, no doubt stimulated the priests to make careful observations and to preserve religiously the record of astronomical phenomena. It was even established that there is a cycle in which eclipses, solar and lunar, repeat themselves, a period (saros) somewhat more than eighteen years and eleven months. Moreover, from the Babylonians we derive some of our most sublime religious and scientific conceptions. They held that strict law governs the apparently erratic movements of the heavenly bodies. Their creation myth proclaims: "Merodach next arranged the stars in order, along with the sun and moon, and gave them laws which they were never to transgress."

The mathematical knowledge of the Babylonians is related on the one hand to their astronomy and on the other to their commercial pursuits. They possessed highly developed systems of measuring, weighing, and counting—processes, which, as we shall see in the sequel, are essential to scientific thought. About 2300 B.C. they had multiplication tables running from 1 to 1350, which were probably used in connection with astronomical calculations. Unlike the Egyptians they had no symbol for a million, though the "ten thousand times ten thousand" of the Bible (Daniel VII: 10) may indicate that the conception of even larger numbers was not altogether foreign to them. They counted in sixties as well as in tens. Their hours and minutes had each sixty subdivisions. They divided the circle into six parts and into six-times-sixty subdivisions. Tables of squares and cubes discovered in southern Babylonia were interpreted correctly only on a sexagesimal basis, the statement that 1 plus 4 is the square of 8 implying that the first unit is 60. As we have already seen, considerable knowledge of geometry is apparent in Babylonian designs and constructions.

According to a Greek historian of the fifth century B.C., there were no physicians at Babylon, while a later Greek historian (of the first century B.C.) speaks of a Babylonian university which had attained celebrity, and which is now believed to have been a school of medicine. Modern research has made known letters by a physician addressed to an Assyrian king in the seventh century B.C. referring to the king's chief physician, giving directions for the treatment of a bleeding from the nose from which a friend of the prince was suffering, and reporting the probable recovery of a poor fellow whose eyes were diseased. Other letters from the same general period mention the presence of physicians at court. We have even recovered the name (Ilu-bani) of a physician who lived in southern Babylonia about 2700 B.C. The most interesting information, however, in reference to Babylonian medicine dates from the time of Hammurabi, a contemporary of the patriarch Abraham. It appears from the code drawn up in the reign of that monarch that the Babylonian surgeons operated in case of cataract; that they were entitled to twenty silver shekels (half the sum for which Joseph was sold into slavery, and equivalent to seven or eight dollars) for a successful operation; and that in case the patient lost his life or his sight as the result of an unsuccessful operation, the surgeon was condemned to have his hands amputated.

The Babylonian records of medicine like those of astronomy reveal the prevalence of many superstitious beliefs. The spirits of evil bring maladies upon us; the gods heal the diseases that afflict us. The Babylonian books of medicine contained strange interminglings of prescription and incantation. The priests studied the livers of sacrificial animals in order to divine the thoughts of the gods—a practice which stimulated the study of anatomy. The maintenance of state menageries no doubt had a similar influence on the study of the natural history of animals.

The Babylonians were a nation of agriculturists and merchants. Sargon of Akkad, who founded the first Semitic empire in Asia (3800 B.C.), was brought up by an irrigator, and was himself a gardener. Belshazzar, the son of the last Babylonian king, dealt in wool on a considerable scale. Excavation in the land watered by the Tigris and Euphrates tells the tale of the money-lenders, importers, dyers, fullers, tanners, saddlers, smiths, carpenters, shoemakers, stonecutters, ivory-cutters, brickmakers, porcelain-makers, potters, vintners, sailors, butchers, engineers, architects, painters, sculptors, musicians, dealers in rugs, clothing and fabrics, who contributed to the culture of this great historic people. It is not surprising that science should find its matrix in so rich a civilization.

The lever and the pulley, lathes, picks, saws, hammers, bronze operating-lances, sundials, water-clocks, the gnomon (a vertical pillar for determining the sun's altitude) were in use. Gem-cutting was highly developed as early as 3800 B.C. The Babylonians made use of copper hardened with antimony and tin, lead, incised shells, glass, alabaster, lapis-lazuli, silver, and gold. Iron was not employed before the period of contact with Egyptian civilization. Their buildings were furnished with systems of drains and flushes that seem to us altogether modern. Our museums are enriched by specimens of their handicraft—realistic statuary in dolerite of 2700 B.C.; rock crystal worked to the form of a plano-convex lens, 3800 B.C.; a beautiful silver vase of the period 3950 B.C.; and the head of a goat in copper about 4000 B.C.

Excavation has not disclosed nor scholarship interpreted the full record of this ancient people in the valley of the Tigris and the Euphrates, not far from the Gulf of Persia, superior in religious inspiration, not inferior in practical achievements to the Egyptians. Both these great nations of antiquity, however, failed to carry the sciences that arose in connection with their arts to a high degree of generalization. That was reserved for another people of ancient times, namely, the Greeks.