Greek Science of the Hellenistic Era

A Sourcebook

Georgia L. Irby-Massie, Paul T. Keyser

• Publisher: Routledge
• Year: 2013
• ISBN:
  9781134556397
• Edition: 1
• Topic: History
• Subtopic: Ancient History
• Index: History

We all want to understand the world around us, and the ancient Greeks were the first to try and do so in a way we can properly call scientific. Their thought and writings laid the essential foundations for the revivals of science in medieval Baghdad and renaissance Europe. Now their work is accessible to all, with this invaluable introduction to c.100 scientific authors active from 320 BCE to 230 CE.
The book begins with an outline of a new socio-political model for the development and decline of Greek science, followed by eleven chapters that cover the main disciplines:
* the science which the Greeks saw as fundamental - mathematics
* astronomy
* astrology and geography
* mechanics
* optics and pneumatics
* the non-mathematical sciences of alchemy, biology, medicine and 'psychology'.
Each chapter contains an accessible introduction on the origins and development of the topic in question, and all the authors are set in context with brief biographies.

Map 1 Greece and the Aegean region.

Map 2 The Mediterranean region.

1

INTRODUCTION

Every person naturally seeks to know.

(Aristotle, Metaphysics 1[980a22])

Greek poets invoked divine Muses to guide their tale, and often began, as before the walls of Troy, in mid-stream. Neither Klio of history nor Ourania of astronomy has appeared for this work, but the story does begin in its middle, after the most-studied period of Greek science (up through Aristotle). Numerous works exist on the early philosophers who speculated about the natural world, as well as on Hippokrates, Plato, and Aristotle. The focus here is the era between Aristotle and the “late-antique” commentators on Aristotle, during which a wide variety of writings were composed, but no single synthesis was standard.

Certain ideas were, however, standard or at least broadly received; and “science” was on the whole studied in a certain context. First, what is covered in this source-book as ‘science’ cannot be precisely distinguished from other intellectual activities. Science borders on philosophy (metaphysics, ethics, and epistemology are excluded), it lies near technology (most material found in books such as Humphrey, Oleson and Sherwood [1998] is excluded), it has affinity with magic (theurgy and all incantations are excluded, but astrology and alchemy are included), and touches on theology (divine cosmogonies and the theology of the soul are excluded). Those distinctions, almost impossible to make for Greek authors before around –400, become clearer in Aristotle, and after. That conceptual territory, adjacent to but not within magic, philosophy, technology, and theology, is what this book undertakes to cover. Next, what was the socio-political context of those Greeks writing such works in this era? Again, precision is impossible, primarily due to lack of evidence. Almost all were male (though note Kleopatra, Maria, Ptolemaïs, and probably the author of Isis to Horus: cf. Irby-Massie [1993]), not unusual in that time and place. Many of these men worked at Alexandria, sponsored in some way by the Ptolemaic kings of Egypt; others seem to have been supported in some way by other wealthy rulers. But many, perhaps most, lived and worked far from those prestigious centers, and depended on their own wealth, that of private patrons, or on fees they charged for teaching and practicing their skill: astrologers, mechanics (especially artillery-makers), and doctors are known to have done so; indubitably others also did. City-states and kingdoms found medicine, mechanics, and even astronomy useful, while all of the topics here treated had some intellectual cachet (i.e., they were among the things one could validly study and debate). Their readers we know far less about, though evidently there was enough interest among the literate classes to elicit these books and many more that are lost.

The earlier period of Greek science (up through Aristotle) had created a legacy of shared assumptions, beliefs, concepts, definitions, goals, problems, and results, the full study of which has filled many a book. It was on these that workers in the period here covered built, modifying them as they saw fit. A brief sketch of some of these developments is in order, which can be no more complete or precise than would be a survey of similar length over Aristotle or Plato (compare Rihll [1999]).

From Eukleidês on, Greek mathematics (Chapter 2) was systematized as a logico-deductive system, employing lengths as its fundamental entity (to represent both geometrical figures and numbers), and describing its project largely in terms of certain problems (Knorr [1986]). Arithmetic as manifested in Heron and Diophantos either developed later, or at least is absent from our earlier sources. The difficulties surrounding the parallel-lines postulate were neither ignored nor seen as critical; infinitesimals were rejected, and irrational lengths (such as the diagonal of the unit square) were regularly handled as a case separate from rational lengths. Among the standard problems were “to double a volume” (i.e., to find what we would call a cube root), to “square” the circle (i.e., to calculate its area), to describe the properties of curved lines constructed in certain ways (e.g., the “parabola”), and to explain the various arithmetical properties of numbers (e.g., divisibility). There was definite influence from Babylonian arithmetic, but its exact extent and nature is unclear.

Once the geocentric hypothesis and the concept of the spherical earth became accepted (well before the period covered in this book), much of the remaining “project” of the study of the sky (astronomia or astrologia, Chapters 3 and 4) involved working out the detailed consequences of that model (Evans [1998]). It was assumed that there would be some ‘simple’ and mathematical picture to explain the observed phenomena, always seen as fundamentally regular. The shift from a concentric-sphere model (as in Aristotle and earlier) to the circular-orbit model is crucial; another key move was the development of trigonometry (the mathematics needed to work with that model). One chief motivation for astronomy was theoretical – the desire to understand the phenomena; but another was calendrical – to regulate the complex Greek luni-solar religious calendars. The desire to predict both lunar and solar eclipses was never fully realized, but lunar eclipses could reliably be forecast from the time of Hipparchos, and increasingly precise predictions of planetary positions were available (culminating with Ptolemy's tables).

A third chief motivation for astronomy was astrology (Chapter 4) – the belief that the motions of the planets affected the earth (most recently in English see Barton [1994] 9–31, 92–113, 179–197). The planets were associated with certain gods, and people remained certain that some kinds of divine influence emanated from them to us, though the kind and extent of that influence was greatly debated. It was more and more widely believed that the kosmos was connected by “sympathy” between its different parts: i.e., that a change in one part caused a corresponding change in others. Both astronomy and astrology are known to have been influenced by Babylonian learning: Hipparchos used their data, their style of prediction (somehow received as Egyptian) became one of the standard modes of Greek astrology, and the divine associations of the planets and many constellations are Babylonian.

The greatly-widened geographical horizon of the Greeks after Alexander contributed to knowledge of much more of the globe, and in the era of this book one of the chief problems of Greek geography (Chapter 5) was how best to map that data about the globe. A variety of techniques was employed, and eventually geometrical projections of a sphere onto a plane were developed. Another chief problem was the determination of the size of the earth, from astronomical observations. Likewise the problem of determining latitude (always expressed in terms of longest and shortest days) and even longitude continued to occupy geographers. The influence of latitude and other geographical factors on the local character of plants, animals, and people also remained an interest. Perhaps the largest bulk of geography in this time was descriptive, which tended to stress the marvelous and extraordinary; Greece remained the ideal central mean between extremes (Romm [1992]).

In the related areas of mechanics (Chapter 6), optics (Chapter 7), and hydrostatics/pneumatics (Chapter 8), the goal was to explain the phenomena through geometry. Each type of behavior offered “paradoxes” which were to be understood as in fact somehow regular. Thus the movement of large weights by small forces, or the causing of small weights to have large impacts was studied by workers in mechanics. Opticians sought to explain optical illusions of various kinds, and to produce astonishing sights, a work encouraged by the leading role of vision in Greek philosophy. Pneumatics workers debated the nature and role of the void in fluids, and applied their art to water-supply, the floating of ships, and the often surprising motion of fluids. In all three fields, one persistent goal was the production of marvels, either as a demonstration of power or of the range of the model, or as a means to elicit financial support.

The project in alchemy (Chapter 9) was to explain the transformations of materials on the basis of the standard four-element model; colors and all other properties were believed to be secondary qualities dependent on elemental composition (Keyser [1990]). A competing model was that substances are composed of atoms, whose shapes and arrangements created secondary qualities. In both models, color seems to have been conceived as a mutable surface property, and substances were believed to have powers to affect and even transform one another. Within that framework, the alchemists achieved broad success, both explanatory and performative, since they were able to “produce” silver, emeralds, dyes, etc. They continued to believe that the production of gold was also possible, but were less able to show success.

In Biology (Chapter 10), one of the chief early goals had been to explain the origin and diversity of life (Lloyd [1983]). In the period of this book, little reference to that is made, apart from the widespread belief that some kinds of small plants and animals were “spontaneously” generated out of nonliving matter. It continued to be assumed that animal behavior was in many respects like human behavior. One chief problem or locus of debate was the extent to which animals could be said to have human rationality. Just as for non-living matter, animals and especially plants were seen as having powers.

Greek medical thought (Chapter 11) typically assumed that health was a balance of factors, or a mean between extremes, without agreement on which (Longrigg [1993]). Many medical writers of this period assumed the factors were the four “humours” – this spelling is used for distinction – but others speak of the balance of blood and pneuma, or of the motion of corpuscles. To a greater extent than in any other area of Greek science, medical thought was segmented into “schools” – patterns of shared concepts to which a medical writer typically declared his allegiance. The “dogmatists” asserted the primacy of Hippokrates and the possibility of rational and theoretical models of health and disease; they typically adhere to the “four humours” model. The Empiricists denied the possibility of rational accounts, and prescribed treatment on the basis of their own and others’ successful experience. Herophilos started a school, which emphasized pharmacy for therapy, the pulse for diagnosis, and dissection for studying the body. Erasistratos and his followers sought cures in balancing the flow of blood and pneuma in the body (although he rejected venesection). Standard treatments continued to include dietary and activity regulation, as well as venesection, enemas, and emetics (to evacuate “bad” material), with surgery more rarely resorted to. Drug remedies, believed to change the state of the body in useful ways, were primarily herbal (with some mineral or animal components), and became increasingly complex mixtures, as the doctors sought to combine and balance the powers of the ingredients (Keyser [1997a]). In addition to the new use of the pulse in diagnosis, and the increasing use of drug mixtures, another change was the practice of human dissection (previous knowledge of human anatomy was based on experience on the battlefield and analogy with animals).

The “psychology” chapter (Chapter 12) is something of a mixed bag, but unified as Greek thought on the physiology, or bodily and physical basis, of the soul (Roccatagliata [1986]). Many Greeks believed that some or all aspects of rational activity (sensation, etc.) could be explained on a physical basis. One persistent problem was the physical location of the soul – some advocated the heart and others the brain. Another was the degree to which character could be understood or even predicted on the basis of the body and its phenomena. Just as for health and illness of the body, it was widely assumed that the health or illness of the soul was determined or affected by the balance of factors in the body.

Such were the concepts and the actors in Greek science of this era. But what was the larger socio-political context, and can we explain why science had the character it did? The origins of Greek science have been much debated, but the most appealing model is that due to Lloyd, who argues that it flourished in the peculiar political context of Greece – city-states with a relatively large political elite possessing a tradition of active and productive debate on significant political questions (Lloyd [1979] 226–267; [1987] 50– 171; 1991; 1992).

In fact, it is an extension of that model that seems best to explain the trajectory of Greek science in this period. Again, this can be no more than a sketch of an argument. In the earliest Greek science in the period up to about –370 (as briefly described in the prolegomenon to each following chapter), what is notable is the persistence of certain notions – and the great variety of the systems proposed. This account is focussed on cosmology and medicine, as relevant to the purpose and as better represented in the surviving sources. That there is kosmic stability beneath kosmic change, that health is a kind of stability, and that the human being and body is an integral part of the kosmos, seem to have been inevitable assumptions. And each system developed to explain the kosmos indeed claims to explain it all – and yet leaves much unexplained and open. These competing and open systems co-existed, and thereby fostered debate – and investigation. In all these early thinkers one finds an over-arching desire for a unifying theory of everything, though details are often wanting. For example, just how do the four elements, or the four humours, in fact explain actual changes in the world or the body? Or again, how do mere rearrangements of atoms explain even the differences between water and wine? That was not the primary goal of these authors. Rather, they were seeking meaning in the natural world. This is perhaps clearest in the writings of the more poetic of the authors, Xenophanes of Kolophon, Parmenides of Elea, and Empedokles of Akragas. Xenophanes writes primarily of the nature of the true divine mind who orders the world properly and rightly – and stably. The earth, he sang, stretched down to infinity, and all things came to be from earth and sea. Parmenides insisted that existence itself, reality as a whole, is divine, uncreated, and immortal. Such Being had for Parmenides certain properties – among them stability and sphericity. For Empedokles, the four “roots” (Earth, Water, Air, and Fire) were divine and imperishable, and the true basis of all existence.

For all of these authors, the goal was to perceive the world as an ordered whole – i.e., as a kosmos. Their theories tended to validate various traditional notions, and also produced a kind of presumptive synthesis, which undergirded most later systems. Despite this prevenient set of assumptions, there was no prevailing “standard model” but rather an “almost-free market” of competing – and interacting – models. A brief list of some of the key concepts and relevant assumptions of this set of systems will be helpful. First of all is the assumption that it is a meaningful and answerable question to ask what is the essential nature of reality, including the nature of ourselves. Second, that we are also able to ask what is the underlying stability in a world of flux. Third, that we can ask for an account of how one thing follows another, that is, an account of the nature of causation. Beyond those three fundamental questions, was a group of paradigmatic notions: (1) the world was an ordered whole, (2) that order included a natural balance and a natural hierarchy, (3) geometric structure had explanatory power, (4) there were persisting simple elements which constituted stuff, and (5) there existed between certain pairs of things a natural harmony or “sympathy.” In particular, with reference to cosmology, it was assumed that all heavenly bodies moved in eternal circles about the central earth; and with reference to the body, it was assumed that a balanced diet and activity (“regimen”) would guard the balanced stability of health, and that a body fallen into imbalance could be restored to balance primarily via diet, drugs, and activity. For those thinkers, there was no contradiction between the notion of a “natural hierarchy” and a “natural harmony” – they saw a harmony between upper and lower, and between rulers and ruled – a perspective we have long since abandoned as illusory.

This more or less coherent collection of rarely or never-questioned assumptions, beliefs, concepts, and definitions formed the basis of all later Greek explanatory syntheses. Examining mathematics, geography, biology, and so on, would add a few items but not substantially alter the picture. Moreover, despite wide agreement on this presumptive synthesis, there was no single “standard model” nor even any grand unified theory of health and disease or of the kosmos. Instead there was a variety of competing models, none dominant, none claiming explanatory totality, and none formalized into a school or self-perpetuating tradition.

The intellectual situation corresponds exactly with the political situation in Greece, as emphasized by Lloyd – contentious public debate, constantly shifting politics, multiple autonomous states. The essence of the argument is that cultural forms and norms become engrained, endemic, and therefore implicit in the thought-process of members of the society. The dominant political paradigm subtly forms ...