Oral Culture

what's science ? The opinion that there was no science in the two thousand years covered by this

book continues to be stated with considerable regularity and dogmatic fervor. If the claim is true, I have written a book about a nonexistent subject—no mean feat, but not my goal. This book proclaims in its title that it will portray the beginnings of Western science over the approximately three millennia ending about the year a.d. 1450. Was there truly such a thing as science in those times? And if the answer is affirmative, was there enough of it to merit book-length coverage?

Before we can answer these questions, we need a definition of “science”—something that turns out to be surprisingly difficult to come by. There is, of course, the dictionary definition, according to which “science” is organized, systematic knowledge of the material world. But this proves to be so gen-eral as to be of little help. For example, do craft traditions and technology count for science, or are science and technology to be distinguished from one another—the former dedicated to theoretical knowledge, the latter to its application? If only theoretical knowledge counts as genuine science, we then need to decide which theories (or which kinds of theory) pass the test. Do astrology and parapsychology, both of which are chock full of theories, count as sciences?

Perceiving that the “theoretical knowledge” criterion is heading toward a dead end, some participants in the debate argue that true science can be recognized by its methodology—specifically, the experimental method, according to which a theory, if it is to be truly scientific, must be built on and tested against the results of observation and experiment. (In the minds of many of its advocates, a series of rigorously defined steps must be employed.) Theories that meet this test are often credited with superior epistemological status or warrant and thus are representative of a privileged way of knowing.

Finally, for many people—scientists and general public alike—true science is defined simply by its content—the current teachings of physics, chemistry, biology, geology, anthropology, psychology, and so forth.

This brief foray into lexicography ought to remind us that many words, especially the most interesting ones, have multiple meanings that shift with the contexts of usage or the practices of specific linguistic communities. Every meaning of the term “science” discussed above is a convention accepted by a sizable group of people, who are unlikely to relinquish their favored usage without a fight. From which it follows that we have no choice but to accept a diverse set of meanings as legitimate and do our best to determine from the context of usage what the term “science” means on any specific occasion.

But where does that leave us? Was there anything in Europe or the Near East in the twenty centuries covered by this book that merits the name “science”? No doubt! Many of the ingredients of what we now regard as science were certainly present. I have in mind languages for describing nature, meth-ods for exploring or investigating it (including the performance of experiments), factual and theoretical claims (stated mathematically wherever possible) that emerged from such explorations, and criteria for judging the truth or validity of the claims thus made. Moreover, it is clear that pieces of the resulting ancient and medieval knowledge were, for all practical purposes, identical to what all parties would now judge to be genuine science. Planetary astronomy, geometrical optics, field biology or natural history, and certain branches of medicine are excellent examples.

This is not to deny significant differences—in motivation, instrumentation, institutional support, methodological preferences, mechanisms for the dissemination of theoretical results, and social function. Despite these differences, I believe that we can comfortably employ the expression “science” or “natural science” in the context of antiquity and the

Middle Ages. In so doing, we declare that the ancient and medieval activities that we are investigating are the ancestors of modern scientific disciplines and therefore an integral part of their history. It is like my relationship to my paternal grandfather. The differences between us may outweigh the similarities; but I am his descendant, bearing to some extent both his genetic and his cultural stamp. And both of us may honorably claim the family name.

There is a danger that must be avoided. If historians of science were to investigate past practices and beliefs only insofar as those practices and beliefs resemble modern science, the result would be serious distortion. We would not be responding to the past as it existed, but examining it through a modern grid. If we wish to do justice to the historical enterprise, we must take the past for what it was. And that means that we must resist the temptation to scour the past for examples or precursors of modern science. We must respect the way earlier generations approached nature, acknowledging that although it may differ from the modern way, it is nonetheless of interest because it is part of our intellectual ancestry. This is the only suitable way of understanding how we became what we are. The historian, then, requires a very broad definition of “science”—one that will permit investigation of the vast range of practices and beliefs that lie behind, and help us to understand, the modern scientific enterprise. We need to be broad and inclusive, rather than narrow and exclusive; and we should expect that the farther back we go, the broader we will need to be.

I will do my best to heed my own advice, adopting a definition of “science” as broad as that of the historical actors whose intellectual efforts we are attempting to understand. This does not mean, of course, that all distinctions are forbidden. I will distinguish between the craft and theoretical sides of science—a distinction that many ancient and medieval scholars would themselves have insisted upon—and I will focus my attention on the latter.2 The exclusion of technology and the crafts from this narrative is not meant as a commentary on their importance, but rather as an acknowledgment of the magnitude of the problems confronting the history of technology and its status as a distinct historical specialty having its own skilled practitioners. My concern will be with the beginnings of scientific theories, the methods by which they were formulated, and the uses to which they were put; and that will prove a sufficient challenge.

A final word about terminology. Until now, I have consistently employed the word “science” to denote the object of our historical study. The time has come, however, to introduce the alternative expressions ``natural philosophy” and “philosophy of nature,” which will also appear frequently in this book. These are expressions that ancient and medieval scholars themselves applied to investigations of the natural world that concentrated on questions of mate-rial causation, as opposed to mathematical analysis. For the latter, the term “mathematics'' did service. And finally, a vocabulary developed for identifying sub disciplines such as astronomy, optics, meteorology, metallurgy, the science of motion, the science of weights, geography, natural history (including both plants and animals), and medicine. Close attention by the reader to context should make the meaning clear in every case.

prehistoric attitudes toward nature From the beginning, the survival of the human race has depended on its ability to

cope with the natural environment. Prehistoric people developed impressive technologies for obtaining the necessities of life. They learned how to make tools, start fires, obtain shelter, hunt, fish, and gather fruits and vegetables. Successful hunting and food gathering (and, after about 7000 or 8000 b.c., settled agriculture) required a substantial knowledge of animal

behavior and the characteristics of plants. At a more advanced level, prehistoric people learned to distinguish between poisonous and therapeutic herbs. They developed a variety of crafts, including pottery, weaving, and metalworking. By 3500 they had invented the wheel. They were aware of the seasons and perceived the connection between the seasons and various celestial phenomena. In short, they knew a great deal about their environment.

But the word “know,” seemingly so clear and simple, is almost as tricky as the term “science”; indeed, it brings us back to the distinction between technology and theoretical science. It is one thing to know how to do things, another to know why they behave as they do. One can engage in successful and sophisticated carpentry, for example, without any theoretical knowledge of stresses in the timbers one employs. An electrician with only the most rudimentary knowledge of electrical theory can successfully wire a house. It is possible to differentiate between poisonous and therapeutic herbs with-out possessing any biochemical knowledge that would explain poisonous or therapeutic properties. The point is simply that practical rules of thumb can be effectively employed even in the face of total ignorance of the theoretical principles that lie behind them. You can have “know-how” without theoretical knowledge.

It should be clear, then, that in practical or technological terms, the knowledge of prehistoric humans was great and growing. But what about theoretical knowledge? What did prehistoric people “know” or believe about the origins of the world in which they lived, its nature, and the causes of its numerous and diverse phenomena? Did they have any awareness of general laws or principles that governed the particular case? Did they even ask such questions? We have very little evidence on the subject. Prehistoric culture is by definition oral culture; and oral cultures, as long as they remain exclusively oral, leave no written remains. However, an examination of the findings of anthropologists studying preliterate tribes in the nineteenth and twentieth centuries, along with careful attention to remnants of prehistoric thought carried over into the earliest written records, will allow us to formulate a few tentative generalizations.

Critical to the investigation of intellectual culture in a preliterate society is an understanding of the process of communication. In the absence of writing, the only form of verbal communication is the spoken word; and the only storehouses of knowledge are the memories of individual members of the community. The transmission of ideas and beliefs in such a culture occurs only in face-to-face encounters, through a process that has been characterized as “a long chain of interlocking conversations” between its members. The portion of these conversations considered important enough to remember and pass on to succeeding generations forms the basis of an oral tradition, which serves as the principal repository for the collective experience and the general beliefs, attitudes, and values of the community.

There is an important feature of oral tradition that demands our attention—namely, its fluidity. Oral tradition is typically in a continuous state of evolution, as it absorbs new experiences and adjusts to new conditions and needs within the community. Now, this fluidity of oral tradition would be extremely frustrating if the function of oral tradition was conceived as the communication of abstract historical or scientific data—the oral equivalent of a historical archive or a scientific report. But an oral culture, lacking the ability to write, certainly cannot create archives or reports; indeed, an oral culture lacks even the idea of writing and must therefore lack even the idea of a historical archive or a scientific report.4 The primary function of oral tradition is the very practical one of explaining, and thereby justifying, the present state and structure of the community, supplying the community with a continuously evolving “social charter.” For example, an account of past events may be

employed to legitimate current leadership roles, property rights, or distribution of privileges and obligations. And in order to serve this function effectively, oral tradition must be capable of adjusting itself fairly rapidly to changes in social structure.

But here we are principally interested in the content of oral traditions, especially those portions of the content that deal with the nature of the universe—the portions, that is, that might be thought of as the ingredients of a worldview or a cosmology. Such ingredients exist within every oral tradition, but often beneath the surface, seldom articulated, and almost never assembled into a coherent whole. It follows that we must be extremely reluctant to articulate the worldview of preliterate people on their behalf, for this cannot be done without our supplying the elements of coherence and system, thereby distorting the very conceptions we are attempting to portray. But we may, if we are careful, formulate certain conclusions about the ingredients or elements of worldview within preliterate oral traditions.

It is clear that preliterate people, no less than those of us who live in modern scientific culture, need explanatory principles capable of bringing order, unity, and especially meaning to the apparently random and chaotic flow of events. But we should not expect the explanatory principles accepted by preliterate people to resemble ours: lacking any conception of “laws of nature” or deterministic causal mechanisms, their ideas of causation extend well beyond the sort of mechanical or physical action acknowledged by modern science. It is natural that in the search for meaning they should proceed within the framework of their own experience, projecting human or biological traits onto objects and events that seem to us devoid not only of humanity but also of life. Thus, the beginning of the universe is typically described in terms of birth, and cosmic events may be interpreted as the outcome of a struggle between opposing forces, one good and the other evil. There is an inclination in preliterate cultures not only to personalize but also to individualize causes, to suppose that things happen as they do because they have been willed to do so. This tendency has been described by H. and H. A. Frankfort:

Our view of causality . . . would not satisfy primitive man because of the impersonal character of its explanations. It would not satisfy him, moreover, because of its generality. We understand phenomena, not by what makes them peculiar, but by what makes them manifestations of general laws. But a general law cannot do justice to the individual char-acter of each event. And the individual character of the event is precisely what early man experiences most strongly. We may explain that certain physiological processes cause a man’s death. Primitive man asks: Why should this man die thus at this moment? We can only say that, given these conditions, death will always occur. He wants to find a cause as specific and individual as the event which it must explain. The event . . . is experienced in its complexity and individuality, and these are matched by equally individual causes.

Oral traditions typically portray the universe as consisting of sky and earth, and perhaps also an underworld. An African myth describes the earth as a mat that has been unrolled but remains tilted, thereby explaining upstream and downstream—an illustration of the general tendency to describe the universe in terms of familiar objects and processes. Deity is an omnipresent reality within the world of oral traditions, though in general no clear distinction is drawn between the natural, the supernatural, and the human; the gods do not transcend the universe but are rooted in it and subject to its principles. Belief in the existence of ghosts of the dead, spirits, and a variety of invisible powers, which magical ritual allows one to control, is another universal feature of oral tradition. Reincarnation (the idea that after

death the soul returns in another body, either human or animal) is widely believed in. Conceptions of space and time are not (like those of modern physics) abstract and mathematical, but are invested with meaning and value drawn from the experience of the community. For example, the cardinal directions for a community whose existence is closely connected to a river might be “upstream” and “downstream,” rather than north, south, east, and west. Some oral cultures have difficulty conceiving of more than a very shallow past: an African tribe, the Tio, for example, cannot situate anybody farther back in time than two generations.

There is a strong tendency within oral traditions to identify causes with beginnings so that to explain something is to identify its historical origins. Within such a conceptual framework, the distinction that we make between scientific and historical understanding cannot be sharply drawn and maybe nonexistent. Thus, when we look for the features of oral tradition that count for worldview or cosmology, they will almost always include an account of origins—the beginning of the world, the appearance of the first humans, the origin of animals, plants, and other important objects, and finally the formation of the community. Related to the account of origins is often a genealogy of gods, kings, or other heroic figures in the community’s past, accompanied by stories about their heroic deeds. It is important to note that in such historical accounts the past is portrayed not as a chain of causes and effects that produce gradual change, but as a series of decisive, isolated events by which the present order came into existence.

These tendencies can be illustrated with examples from both ancient and contemporary oral cultures. According to the twentieth-century Kuba of equa-torial Africa,

Mboom or the original water had nine children, all called Woot, who in turn created the world. They were, apparently in order of appearance: Woot the ocean; Woot the digger, who dug riverbeds and trenches and threw up hills; Woot the flowing, who made rivers flow; Woot who created woods and savannas; Woot who created leaves; Woot who created stones; Woot the sculptor, who made people out of wooden balls; Woot the inventor of prickly things such as fish, thorns, and paddles; and Woot the sharpener, who first gave an edge to pointed things. Death came to the world when a quarrel between the last two Woots led to the demise of one of them by the use of a sharpened point.

Notice how this tale not only accounts for the origin of the human race and the major topographical features of the Kuba world, but also explains the invention of what the Kuba clearly considered a critically important tool—the sharpened object.

Similar themes abound in early Egyptian and Babylonian creation myths. According to one Egyptian account, in the beginning the sun-god, Atum, spat out Shu, the god of air, and Tefnut, the goddess of moisture. Thereafter,

Shu and Tefnut, air and moisture, gave birth to earth and sky, the earth-god Geb and the sky-goddess Nut. . . . Then in their turn Geb and Nut, earth and sky, mated and produced two couples, the god Osiris and his consort Isis, the god Seth and his consort Nephthys. These represent the creatures of this world, whether human, divine, or cosmic.

A Babylonian myth attributes the origin of the world to the sexual activity of Enki, god of the waters. Enki impregnated the goddess of the earth or soil, Ninhursag. This union of water and earth gave rise to vegetation, represented by the birth of the goddess of plants, Ninsar. Enki subsequently mated first with his daughter, then with his granddaughter, to produce

various specific plants and plant products. Ninhursag, angered when Enki devoured eight of the new plants before she had the opportunity to name them, pronounced a curse on him. Fearing the consequences of Enki’s demise (apparently a drying up of the waters), the other gods prevailed on Ninhursag to withdraw the curse and heal Enki of the various ailments induced by the curse, which she did by giving birth to eight healing deities, each associated with a part of the body—thus accounting for the origin of the healing arts.

It will be convenient to pause for a moment on the healing arts, which can serve to illustrate some important characteristics of oral cultures. There can be no doubt that healing practices were extremely important in ancient oral cultures, where primitive conditions made disease and injury everyday realities. Minor medical problems, such as wounds and lesions, were no doubt treated by family members. More dramatic ailments—major wounds, broken bones, severe and unexpected illness—might require assistance from some-body with more advanced knowledge and skill. A certain amount of medical specialization thus came into existence: some members of the tribe or the village became known for herb-gathering ability, proficiency in the setting of bones or the treatment of wounds, or experience in assisting at childbirth.

But so described, the primitive medicine practiced in preliterate societies sounds remarkably like a rudimentary version of modern medicine. A more careful look reveals the healing arts within oral cultures to be inseparable and indistinguishable from religion and magic. The “wise woman” or the “medicine man” was valued not simply for pharmaceutical or surgical skill, but also for knowledge of the divine and demonic causes of disease and the magical and religious rituals by which it could be treated. If the problem was a splinter, a wound, a familiar rash, a digestive complaint, or a broken bone, the healer responded in the obvious way—by removing the splinter, binding the wound, applying a substance (if one were known) that would counteract the rash, issuing dietary prohibitions, and setting and splinting the broken limb. But if a family member became mysteriously and gravely ill, one might suspect sorcery or invasion of the body by an alien spirit. In such cases, more dramatic remedies would be called for—exorcism, divination, purification, songs, incantations, and other ritualistic activities.

One last feature of belief in oral cultures (both ancient and contemporary) demands our attention—namely, the simultaneous acceptance of what seems to us incompatible alternatives, without any apparent awareness that such behavior could present a problem. Examples are innumerable, but it may suffice to note that the story of the nine Woots related above is one of seven (or more) myths of origin that circulate among the Kuba, while the Egyptians had a variety of alternatives to the story of Atum, Shu, Tefnut, and their offspring; and nobody seemed to notice, or else to care, that all of them could not be true. Add to this the seemingly “fanciful” nature of many of the beliefs described above, and the question of “primitive mentality” is inevitably raised: did the members of preliterate societies possess a mentality that was prelogical or mystical or in some other way different from our own; and, if so, exactly how is this mentality to be described and explained?

This is an extremely complex and difficult problem that has been hotly debated by anthropologists and others for the better part of the past century, and I am not likely to resolve it here. But I can at least offer a word of methodological advice: namely, that it is wasted effort, contributing absolutely nothing to the cause of understanding, to spend time wishing that preliterate people had employed a conception and criteria of knowledge that they had never encountered—a conception, in the case of prehistoric people, that was not invented until centuries later. We make no progress by assuming that preliterate people were trying, but failing, to live up to our conceptions of knowledge and truth. It requires only a

moment of reflection to realize that they were operating within quite a different linguistic and conceptual world, and with different purposes; and it is in the light of these that their achievements must be judged.

The stories embodied in oral traditions are intended to convey and reinforce the values and attitudes of the community, to offer satisfying explanations of the major features of the world as experienced by the community, and to legitimate the current social structure; stories enter the oral tradition (the collective memory) because of their effectiveness in achieving those ends, and as long as they continue to do so there is no reason to question them. There are no rewards for skepticism in such a social setting and few resources to facilitate challenge. Indeed, our highly developed conceptions of truth and the criteria that a claim must satisfy in order to be judged true (internal coherence, for example, or correspondence with an external reality) do not generally exist in oral cultures and, if explained to a member of an oral culture, would be greeted with incomprehension. Rather, the operative principle among preliterates is that of sanctioned belief—the sanction in question emerging from community consensus.

Finally, if we are to understand the development of science in antiquity and the Middle Ages, we must ask how the preliterate patterns of belief that we have been examining yielded to, or were supplemented by, a new conception of knowledge and truth (represented most clearly in the principles of Aristotelian logic and the philosophical tradition it spawned). A necessary condition, if not the full explanation, was the invention of writing, which occurred in a series of steps. First, there were pictographs, in which the written sign stood for the object itself. Around 3000 b.c. a system of word signs (or logograms) appeared, in which signs were created for the important words, as in Egyptian hieroglyphics. But in hieroglyphic writing, signs could also stand for sounds or syllables—the beginnings of syllabic writing. The development of fully syllabic systems about 1500 b.c. (that is, systems in which all monosyllabic signs were discarded) made it possible and, indeed, reasonably easy for people to write down everything they could say. And finally, fully alphabetic writing, which has a sign for each sound (both consonants and vowels), made its appearance in Greece about 800 b.c. and became widely disseminated in Greek culture in the sixth and fifth centuries.

One of the critical contributions of writing, especially alphabetic writing, was to provide a means for the recording of oral traditions, thereby freezing what had hitherto been fluid, translating fleeting audible signals into enduring visible objects.16 Writing thus served a storage function, replacing memory as the principal repository of knowledge. This had the revolutionary effect of opening knowledge claims to the possibility of inspection, comparison, and criticism. Presented with a written account of events, we can compare it with other (including older) written accounts of the same events, to a degree unthinkable within an exclusively oral culture. Such comparison encourages skepticism and, in antiquity, helped to create the distinction between truth, on the one hand, and myth or legend, on the other; that distinction, in turn, called for the formulation of criteria by which truthfulness could be ascertained; and out of the effort to formulate suitable criteria emerged rules of reasoning, which offered a foundation for serious philosophical activity.

But giving permanent form to the spoken word does not merely encourage inspection and criticism. It also makes possible new kinds of intellectual activity that have no counterparts (or only weak ones) in an oral culture. Jack Goody has argued convincingly that early literate cultures produced large quantities of written inventories and other kinds of lists (mostly for administrative purposes), far more elaborate than anything an oral culture could conceivably produce; and, moreover, that these lists made possible new kinds of inspection

and called for new thought processes or new ways of organizing thoughts. For one thing, the items in a list are removed from the context that gives them meaning in the world of oral discourse, and in that sense they have become abstractions. And in this abstract form they can be separated, sorted, and classified according to a variety of criteria, thereby giving rise to innumerable questions not likely to be raised in an oral culture. To give a single example, the lists of precise celestial observations assembled by early Babylonians could never have been collected and transmitted in oral form; their existence in writing, which allowed them to be minutely examined and compared, made possible the discovery of intricate patterns in the motions of the celestial bodies, which we associate with the beginnings of mathematical astronomy and astrology.

Two conclusions may be drawn from this argument. First, the invention of writing was a prerequisite for the development of philosophy and science in the ancient world. Second, the degree to which philosophy and science flourished in the ancient world was, to a very significant degree, a function of the efficiency of the system of writing (alphabetic writing having a great advantage over all of the alternatives) and the breadth of its diffusion among the people. We see the earliest benefits of the use of word signs or logograms in Egypt and Mesopotamia, beginning about 3000 b.c. However, the difficulty and inefficiency of logographic writing inevitably limited its diffusion and made it the property of a small scholarly elite. In sixth-and fifth-century Greece, by contrast, the wide dissemination of alphabetic writing contributed to the spectacular development of philosophy and science. We must not imagine that literacy was sufficient of itself to produce the “Greek miracle” of the sixth and fifth centuries; other factors no doubt contributed, including prosperity, new principles of social and political organization, contact with Eastern cultures, and the introduction of a competitive style into Greek intellectual life. But surely a fundamental element in the mix was the emergence of Greece as the world’s first widely literate culture.

The beginnings of science in egypt and mesopotamia The earliest roots of what would become Western science are to be found in ancient

Mesopotamia (the region between the Tigris and Euphrates Rivers, site of ancient Babylonia and Assyria) and Egypt (the Nile River and its environs)—see map 4.1. I have said enough about creation myths in the preceding section to reveal key features of Egyptian and Mesopotamian cosmogony (concerned with the origins of the universe) and cosmology (concerned with the structure of the universe). Here I will restrict myself to the Egyptian and Mesopotamian contribution to several other disciplines that subsequently found a place within Greek and medieval European science: mathematics, astronomy, and medicine. The evidence is scanty by comparison with materials available on Greek science, but sufficient to convey a general picture.

The Greeks themselves believed that mathematics originated in Egypt and Mesopotamia. Herodotus (fifth-century b.c.) reported that Pythagoras traveled to Egypt, where he was introduced by priests to the mysteries of Egyptian mathematics. From there, according to ancient tradition, he was carried captive to Babylon, where he came into contact with Babylonian mathematics. Eventually, he made his way home to the island of Samos, bearing gifts of Egyptian and Babylonian mathematical treasure to the Greeks. Whether this and similar tales regarding other mathematicians are historically accurate or legendary is less important than the larger truth they convey—namely, that the Greeks were (and knew they were) the beneficiaries of Egyptian and Babylonian mathematical knowledge.

By about 3000 b.c., the Egyptians developed a number system that was decimal in character, employing a different symbol for each power of 10 (1, 10, 100, and so forth). These symbols could be lined up, as in Roman numerals, to form any desired number. Thus if | represented 1, and ౧ represented 10, then the number 34 could be expressed as .||||౧౧౧ By about 1800 b.c. additional symbols had been devised for other numbers, so that, for example, 7 could be represented by a sickle rather than by seven vertical strokes. Addition and subtraction were simple operations in Egyptian arithmetic, performed as with Roman numerals, but multiplication and division were extremely clumsy; and the generalized concept of a fraction was unknown, the general rule allowing only unit fractions (fractions with a numerator of 1). Elementary problems of the following type could be solved: if one-seventh of a quantity is added to the quantity, and the sum equals 16, how large is the quantity?

Egyptian geometrical knowledge appears to have been oriented toward practical problems, including those of surveyors and builders. Egyptians were able to calculate the areas of simple plane figures, such as the triangle and the rectangle, and the volumes of simple solids, such as the pyramid. For example, to find the area of a triangle they took one-half the length of the base times the altitude; and, to find the volume of a pyramid, one-third the area of the base times the altitude. For calculating the area of a circle, the Egyptians worked out rules that correspond to a value for of about 3.17. Finally, in one of the most obvious areas of applied mathematics, the Egyptians devised an official calendar consisting of twelve months of thirty days each, plus an additional five days at the end of the year—a calendar substantially simpler, because of its fixed character, than contemporary Babylonian calendars and those of the early Greek city-states, which attempted to take into account the lunar, as well as the solar, cycle.

The contemporary mathematical achievement in Mesopotamia was an order of magnitude superior to that of the Egyptians. Clay tablets (see fig. 1.1) recovered in large quantities reveal a Babylonian number system, fully developed by about 2000 b.c., that was simultaneously decimal (based on the number 10) and sexagesimal (based on the number 60). We retain sexagesimal numbers today in our system for measuring time (60 minutes to an hour) and angles (60 minutes in a degree and 360 degrees in a circle). The Babylonians had separate symbols for 1 (🔽) and 10 (⬅); these could be combined like Roman numerals to form numbers up to 59. The number 32, for example, would be expressed by three of the tens symbol plus two of the units symbol, as in table 1.1.

But beyond 59 an important difference appears. Instead of forming the number 60 by lining up six symbols for 10, the Babylonians used a place system similar to our own. In our number 234, the numeral 4, situated in the units column, signifies simply the number 4; the numeral 3, situated in the tens column, represents the number 30; while the numeral 2, situated in the hundreds column, stands for the number 200. Thus 234 is 200 30 4. The Babylonian place system worked similarly, except that successive columns rep-resent powers of 60 rather than powers of 10. Thus in the second example in table 1.1, the two-unit symbols in the 60 columns represent not 2, but 2 60 120; and in the third example the unit symbol in the 602 columns represents not 1 but 1 602 3600. There was no equivalent of the decimal point by which to locate the units column, and this information would therefore have to be inferred from context. Multiplication tablets, tables of reciprocals, and tables of powers and roots were used to facilitate calculation. One of the great advantages of the sexagesimal system was the ease with which calculations could be performed using fractions.

The full superiority of Babylonian mathematics over its Egyptian counterpart is evident when we turn to more difficult problems, which we would solve algebraically.

Historians of mathematics sometimes refer to these problems as “algebra”—useful shorthand for this aspect of the Babylonian mathematical enterprise, perhaps, but misleading if it is taken to mean that they practiced genuine algebra—that is, that they had a generalized algebraic notation or an understanding of what we consider algebraic rules. What we can safely say is that Babylonian mathematicians used arithmetical operations to solve problems for which we would employ a quadratic equation. For example, we find many Babylonian tablets, including teaching texts, demonstrating how to solve problems such as the following: given the product of two numbers and their sum or difference, find the two numbers.

The heavens have been objects of observation and speculation since the dawn of human existence. But our first evidence of close, systematic observation, measurement, and cataloging of the stars and planets is found among Babylonians during the second-millennium b.c. Astronomical activity in other ancient cultures (Greece, India, and Egypt) not only emerged later, but also apparently owed its existence to Babylonian influence.24 It would be reasonable to suppose that Babylonian astronomy grew naturally out of Babylonian mathematics, as the riches of the latter were applied to celestial phenomena. But reality has a way of violating our reasonable expectations. It is true that Babylonians eventually developed a predictive mathematical astronomy, but not until centuries of celestial divination (the art of reading the heavenly signs as predictors of future events) had paved the way.

So the story begins with Babylonian divination. It was universally believed within ancient Near Eastern cultures that a wide range of natural phenomena, including those associated with the heavens, concealed messages from the gods—signs or omens—that might be deciphered and interpreted by the adept. The goal of the scholar-scribes who claimed this as their task was to learn the language of the gods, the meaning of those signs, in order to advise their clients how to take appropriate measures to evade, mitigate, or otherwise prepare for the promised event—the defeat of an army, a flood, a stillborn child, a time of peace, a promise of wealth or longevity, or some other event, favorable or unfavorable, personal or public. The gods were believed to speak through all sorts of terrestrial objects or events, including animal entrails, dreams, malformed births, the “color of a dog that urinates on a man,” but also (important for our purposes) through celestial phenomena. Astronomical phenomena probably drew special attention because of their apparent regularity, their celestial location, and identification of the planets with the gods. In any case, by the middle of the first millennium b.c. clay tablets containing nonmathematical diaries, almanacs, and numerical planetary tables (ephemerides) were readily available. These documents provided the resources required for calculation of time and place of a variety of planetary and lunar phenomena, including eclipses, conjunctions (two or more planets meeting in their celestial rounds), and first and last visibilities of planets in the night sky. This was the beginning of computational astronomy.

By the end of the fifth-century b.c., Babylonian celestial divination had expanded to embrace horoscopic astrology, which used planetary positions at the moment of birth (or near the date of birth for such exceptional phenomena as lunar eclipses) to predict individual fortunes. The exact relationship between this new form of divination and pre-existing Babylonian computational astronomy is obscure and a matter of dispute among experts.26 What is clear is that Babylonian horoscopic astrology at least rubbed shoulders with Babylonian computational astronomy and absorbed its aims and methodology. When this astrology was subsequently communicated to Hellenistic Greeks in the third and second centuries b.c., it was an astrology/astronomy (the two were inseparable) that had acquired

both computational aims and numerical methods. And what is of critical importance, the Greek astronomy of the Hellenistic period took its shape—its commitment to computational aims and quantitative methods—from this Babylonian endowment. As a result, the astronomical enterprise set out on a course that would culminate millennia later in the achievements of Nicolaus Copernicus, Johannes Kepler, and others.

The final area of Egyptian and Mesopotamian achievements to be considered in medical. A number of Egyptian medical papyri (written in the period 2500–1200 b.c.) have survived, and these offer us a fragmentary picture of the healing arts in ancient Egypt. From several of the papyri it becomes clear that a principal cause of disease was thought to be invasion of the body by evil forces or spirits. Relief was to be gained through rituals designed to appease or frighten the spirits—exorcism, incantation, purification, or the wearing of an appropriate amulet. The gods could be appealed to for protection: a prayer to the god Horus, found in the Leyden papyrus, reads in part, “Hail to thee, Horus. . . . I come to thee, I praise thy beauty: destroy thou the evil that is in my limbs.”30 Certain gods came especially to be associated with healing functions or healing cults: Thoth, Horus, Isis, and Imhotep. The view that each bodily organ was ruled by a specific god, who could be invoked for healing of that organ, seems to have been widespread. And all of this ritual, of course, required the assistance of an expert who was of acknowledged purity, who knew the required incantations, and who could assure that the ritual was properly performed; this was the priest-healer.

Healing therapies in ancient Egypt were not limited to prayer, incantation, and ritual. Pharmacological remedies, prepared from animal, vegetable, or mineral substances, were also widespread—though their effectiveness was believed to depend on preparation and administration under appropriate ritual conditions. The Ebers papyrus (written about 1600 b.c., but contain-ing material copied from much older texts) contains medical recipes for dealing with diseases of the skin, eyes, mouth, extremities, digestive and reproductive systems, and other internal organs; for treating wounds, burns, abscesses, ulcers, tumors, headaches, swollen glands, and bad breath.

Surgery is dealt with in another papyrus, known as the Edwin Smith papyrus (written about the same time as the Ebers papyrus), which contains a surgical manual that systematically describes the treatment of wounds, fractures, and dislocations. One of the notable features of the Ebers and Edwin Smith papyri is the careful arrangement of case studies, beginning with a description of the problem and proceeding to diagnosis, verdict (as to whether or not the ailment is treatable), and treatment.

Mesopotamian medicine displays many of the same characteristics as Egyptian healing practices. Babylonian clay tablets, like Egyptian papyri, contain case studies, systematically organized by type, many of them revealing careful observation of symptoms and intelligent prognosis. Mesopotamian healers displayed equal skill in surgery and the preparation of pharmaceutical remedies. As in Egypt, a certain amount of medical specialization developed—different categories of healers coming to have somewhat diff er-ent specialties and functions. And again we find healing intimately mingled with religion and with practices that we would now view as magical. Disease was regarded as the result of invasion of the body by evil spirits (owing to fate, carelessness, sin, or sorcery). Therapy was directed toward elimination of the invading spirit through divination (including the interpretation of astrological omens), sacrifice, prayer, and magical ritual.

This brief sketch of Egyptian and Mesopotamian contributions to mathematics, astronomy, and the healing arts offers us a glimpse of the beginnings of the Western scientific tradition, as well as a background against which to view the Greek achievement.

There is no doubt that the Greeks were aware of the work of their Egyptian and Mesopotamian predecessors, and benefited from it. In the chapters that follow, we will see how these products of Egyptian and Mesopotamian thought entered and helped shape Greek natural philosophy.