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  Hero also invented many other toys, including temple doors which opened by steam power. The Greeks were inventive, and their technology did progress. In particular, devices relating to warfare improved, as did methods of producing food. Overall, though, they failed to establish a fruitful relationship between technology and the sciences at a general level.

  Figure 32: Hero’s steam engine.

  The Origins of Alchemy and Astrology

  There were two other disciplines that had a considerable influence over Western thought prior to the scientific revolution, and whose genesis can be traced back to ancient Greece. These were astrology and alchemy. Why mention these in a book on science? Firstly, in the ancient world there were significant thinkers who considered both astrology and alchemy to be sciences. Secondly, ancient astrology and alchemy were significantly different from their modern counterparts, as were ancient cosmology and matter theory. It is possible that both ancient astrology and alchemy had a different relation to the science of their day.

  Ancient astrology and alchemy were both considerably broader in their conception than they are generally given credit for, and there was a wide spectrum of views on how they might work. Alchemy was not merely the search for the transmutation of base metals into gold. Rather, it dealt with the transformation of less valuable things into more valuable things in general. Astrology dealt with the influence of the heavens on the earth in general, and not just on human beings. The greatest of the ancient astronomers, Ptolemy, who was also hugely influential in the history of astrology, set down the evidence in favour of astrology. He began by mentioning the effect of the motions of the sun on the seasons and on the seasonal behaviour of animals and plants, and the effect of the moon on the tides and on the nocturnal behaviour of animals and plants. These effects were undeniable, and were taken to be part of astrology. Only later did Ptolemy move on to the effects that the heavenly bodies may have on humans. Ptolemy’s book the Tetrabiblos was enormously influential in astrology until the seventeenth century.

  The origins of astrology followed the lines that we have seen for astronomy and medicine. The Babylonians and the Egyptians both studied the heavens and produced astrological portents. It was the Greeks who provided a theoretical basis for astrology. Aristotle himself was not interested in astrology, but his cosmology was used by many who were. The key point was that Aristotle believed that the four elements would have separated out into concentric rings of earth, water, air and fire, had it not been for the action of the sun in stirring up these elements. There was a sense, then, in Aristotle’s cosmology, that the sun was responsible for everything that happened on earth. Clearly, the sun had a heating and drying effect. In addition to this, some supposed that the moon had a moistening and cooling effect. Since hot, cold, wet and dry were the pairs of primary contraries which underpinned earth, water, air and fire, the sun and moon could affect anything on the earth, including perhaps human beings. The means for the transmission of astrological influence therefore depended only on Aristotle’s cosmology and his matter theory. It is important to stress that there was nothing mystical or supernatural about Aristotle’s cosmology or his theory of matter. Ancient astrology done in this manner could meet one of the key modern objections to astrology. This is: how do the heavenly bodies affect the earth in a significant manner, without falling back onto anything implausible, supernatural or mystical? Indeed, ancient astrology could meet many of the standard objections to astrology, at least in principle. The fact that astrology was construed so broadly meant that some of the predictions (the more meteorological sort, or those pertaining to the seasonal or nocturnal behaviour of animals) could be quite precise, instead of vague and untestable. So there seemed to be empirical evidence in favour of astrology, when conceived this broadly. Astrology, as formulated by Ptolemy, was not based on outdated astronomy and cosmology. It was based on Ptolemy’s latest discoveries in these fields. Astrology had not yet proved itself incapable of making any progress, and to many it seemed as plausible a science as many other ancient sciences which were still being developed.

  One can see why, in an ancient context, some people would have believed astrology to be a science. There were also many who objected, and there were fierce debates about whether astrology worked at all, and whether it could tell us anything about humans. Not all astrology was done in an Aristotelian manner. Plato’s philosophy could also be used to underpin astrology, and there were many other possible bases. There was a broad spectrum of views on how astrology might work. At one end we have the Aristotelian interpretation, requiring nothing mystical or supernatural. The Stoics, with their strong belief in determinism, were also interested in astrology. Moving along the spectrum, the macrocosm/microcosm relationship could also be used to support astrology, if changes in the universal, macrocosmic mind (i.e., the heavens) were reflected in microcosmic minds, those of humans. At the far end of this spectrum were mystical or supernatural ideas on how astrology might work.

  Alchemy had a slightly different status to astrology in the ancient world. While there was considerable debate about whether astrology was a science, alchemy was more generally accepted. The origins of alchemy are similar to those of astrology. There was a long tradition of metal working in Egypt, and a good deal of practical knowledge. The Stockholm and Leyden papyri show the Egyptians to have been interested in the production of gold, silver, jewellery and dyestuffs. Again, the Greeks provided the theoretical basis for thinking about alchemy. If we ask how people thought alchemy might work, then we need to go back to Aristotle again, this time to his theory of matter. As we have seen, Aristotle believed there to be four elements: earth, water, air and fire; and two pairs of contrary qualities which underpinned these elements: hot and cold, wet and dry. These elements were by no means fixed. Transmutation could happen quite easily, and without recourse to anything magical or unnatural. If water (cold and wet) was heated, it became air (hot and wet). Aristotle believed all things to be made of the four elements. Metals, including gold, were a combination of earth and water. If the right process could be found to alter the proportions of hot, dry, wet and cold, then one substance could be changed into another. Aristotle also believed that metals were generated in the ground. Thus, there was a process by which metals, including gold, were formed from other substances. Again, for Aristotle this was an entirely natural process, similar to the way in which we might say that coal forms in the ground. An alchemist might quite reasonably hope to replicate and perhaps accelerate this process.

  Many other processes which increase the value of something were thought of in this way as well, e.g., the production of dyestuffs. So ancient alchemy could be conceived of entirely within the framework of Aristotle’s theory of matter, about which there was nothing mystical or supernatural. This theory was hugely influential in the ancient world. Many alchemists did think about alchemy in precisely these terms. We can therefore see why, in the ancient world, some people would have been happy to call alchemy a science. As with astrology, there were many ways in which one could theorise alchemy. These ranged from a strict Aristotelian basis, to other theories of matter, including the active and passive principles of the Stoics, to outright mysticism and supernatural ideas.

  The Decline of Greek Science?

  All Good Things Must Come to an End

  Science in the ancient world eventually went into a decline, although not until the later stages of the Western Roman empire. Certainly, science was still going strong in the first and second centuries AD, with the works of Ptolemy and Galen. There were important later thinkers such as Philoponus, who produced criticisms of Aristotle, Simplicius, a commentator on Aristotle’s scientific works, and Iamblichus, a follower of Plato who stressed the importance of mathematics in science. However, the general trend in the latter part of antiquity was towards less creativity and activity in science. One reason for this may have been the later fragmentation of the Roman empire, leaving less time and fewer resources to investigate either phil
osophy or the natural world. Another reason may have been the rise of Christianity. While early Christianity was not uniformly hostile to science, there were certainly powerful tendencies to look to the spiritual rather than the physical, and to do away with pagan – and in particular Greek pagan – thinking. So Tertullian (c. 160–225 AD) said:

  We need not be afraid if the Christian does not know the powers and the number of the elements, the motions and eclipses of the heavens, the nature of the animals, plants and stones … It is sufficient for the Christian to believe that the cause of everything created, whether in heaven or on earth, visible or invisible, is the goodness of the Creator, of the one true God.

  Slightly later, in 390 AD, we can find Augustine (354– 430) saying:

  What has Athens to do with Jerusalem, the Academy to do with the Church, the heretic to do with the Christian? … We have no need for curiosity after Jesus Christ, and no need of investigation after the gospel. Firstly we believe this, that there is nothing else that we need to believe.

  Hermias at least displays some sense of humour when he says of the Stoics:

  Will you listen to the nonsense their philosophers speak, when they say that fire is God? They mistake the deity for their destination.

  The Creation of Science

  It was, then, the ancient Greeks who were the originators of science, although not, it must be said, without considerable contributions from other cultures. But it was the Greeks who took the technologies of earlier civilisations, most notably those of the Babylonians and the Egyptians, and turned them into science. Equally, there have been other contributors to the tradition which has led to modern science. The Arabic/Islamic culture did a great deal to preserve, and then extend and transform, Greek scientific thinking during and after the decline of the Roman empire. Much of this was transmitted to the West, helping to rouse it from the dark ages and push it on towards the Renaissance and the scientific revolution. The Romans contributed a great deal of technology, even if their scientific achievements were meagre. Technology and scientific ideas from China, travelling to the West along the trade routes, were also important influences for Western science.

  The ultimate origins of science lay with the Greeks, though. They rejected explanation in terms of myths and capricious gods, and considered their cosmos to be an entirely natural and well-ordered place. In distinguishing between the natural and the supernatural, they effectively discovered nature. They began to use theories to describe and understand their cosmos. These theories were couched in natural terms, and importantly could be discussed and improved upon in ways that myths could not. It is the rapid increase in the sophistication of their theories that is perhaps the most remarkable thing about the ancient Greeks. Wherever one looks – in cosmology, theory of matter, medicine – one sees them making huge conceptual leaps and arriving at new, better theories. We can also see the Greeks developing means to resolve debates about theories and being conscious of a distinction between science and technology.

  That is what happened among the early Greeks to establish science. We might also ask: why did science begin with the ancient Greeks? Why, in particular, did science begin with the Milesians? To say that there was a Greek ‘miracle’ which brought about the birth of both science and philosophy would not explain anything, and would ignore one of the key lessons of the Milesians. While the Milesians achieved a good deal, it is important to put their achievement into perspective. They neither created science from scratch, nor produced the finished article. They were considerably indebted to other civilisations, especially the Babylonians and the Egyptians. One of the most important things about the Milesians was not the actual quality of their theories, but that they conceived of the idea of a cosmos as an orderly and natural place which could be explained by theories. This, along with the intellectual and religious toleration of ancient Greece, allowed Greek science and philosophy to develop rapidly. The other pre-Socratics, then Plato, Aristotle and the Hellenistic thinkers carried forward this programme of explaining the cosmos in natural terms. The Greek achievement was the work of many hands over a great period of time. The contribution of the Milesians was good, and was seminal, but it was not miraculous. They themselves would have been the first to argue that.

  The conditions which aided the Greeks were their lack of a central religion and hierarchical organisation, and freedom of expression, allied to a society affluent enough for some people to have the leisure time to investigate questions about the nature of the world. In addition, the technological bases in some disciplines (geometry, astronomy, medicine) were already in place, so the time for a transformation to science was ripe. Greek society, with its love of criticism, debate and knowledge for its own sake, proved to be an immensely fertile soil, once the seeds of science had been sown.

  Greek science had distinctive strengths and weaknesses. In very broad outline, the great strengths and achievements were almost all intellectual and theoretical, the weaknesses mainly practical. The fact that Greek philosophy and science were so closely intertwined was a double-edged sword. It allowed the Greeks to develop what was so desperately needed – a natural conception of the world about us, and a theoretical framework for the sciences. It also allowed them to break with mythopoeic thought. The other side of this situation is that some, though by no means all, of these philosopher-scientists were interested only in the philosophical and theoretical aspects of science, and neglected the practical aspects.

  Undoubtedly, the strongest areas of Greek science were those in which there was no need for observation, experiment or a strong link with technology, or in which, for some special reason, the Greeks inherited a good deal of empirical data or had no objection to gathering such data. So Greek mathematics and geometry were strong, because these disciplines, as conceived by the Greeks, did not require observation and experiment. Even here, though, the more theoretical work of the Greeks grew out of the practical mathematics and geometry drawn from Babylonian and Egyptian sources. Greek astronomy was strong, because it had access to Babylonian and Egyptian records, and observing the heavens was accepted as a dignified pursuit. Greek cosmogony and cosmology was also rich in ideas, if a little short on empirical confirmation of them (though, in fairness, cosmology really became an observational discipline only in the twentieth century). Greek medicine was relatively strong too, again partly because it inherited a good deal of practical knowledge from the Babylonians and Egyptians, and partly because medicine in ancient Greece was a highly competitive business. The Hippocratics needed to develop effective treatments, as far as was possible in the ancient world, and realised that to do so they must make careful observations, experiment with various possible treatments, and make full use of whatever technology of healing was available.

  The major weakness in ancient Greek science was a lack of appreciation of the proper role of experiment, observation and technology. Experiment, to some extent, was seen as manual labour, and as such beneath the dignity of a ‘gentleman’ philosopher. Xenophon (c. 430–354 BC), a contemporary of Plato and Aristotle, said that:

  What are called the mechanical arts are spoken against, and, naturally, are held in utter contempt in the cities. They ruin the bodies of the workmen and overseers, compelling them to be seated and to live in the shade, spending the day at the fire.

  The Greeks were never particularly good at technology (the Romans were much better), nor did they develop a fruitful relationship between technology and science. The prime example is that of Hero’s engine. Hero invented a steam engine which could produce rotary motion. A crude, very low-powered engine, but an engine nevertheless. What did the Greeks think of this? Was it a source of power that could possibly be used in many situations? No. It was an interesting toy, a party-piece to impress people with. Because of this sort of attitude, the Greeks never put the necessary developmental work into their technology. They had no real appreciation that a fruitful liaison between science and technology could lead to inventions which would better the lo
t of society in general, and indeed would improve their science. Perhaps this was due to their slave-based culture (there was no need for labour-saving devices), or the stigma of manual work, or the nature of the aristocratic Greek philosophers. Whatever the answer, this was a weakness of Greek science.

  There were also some more specific weaknesses. While the Greeks did many wonderful things in cosmogony and cosmology, there was a fundamental limitation which coloured all of their work. They never developed a conception of gravity. They were forced to explain its effects by means of other theories, and this affected the nature of all of those theories. From the early ‘parallel’ conception of the cosmos, to the ‘centrifocal’ conception, to the sophisticated ideas of later antiquity, the struggle to account for gravitational phenomena coloured Greek cosmology. Some of the Greeks believed in a like-to-like principle, while Aristotle’s theory of natural place came to be dominant. The Greeks had no proper conception of force as we understand it, nor did they develop the idea of relative motion. A combination of these factors led the Greeks to believe that the earth was immobile. They believed that if it moved there would be fierce winds; they could not see how it would hold together, nor why we would stick to its surface if it was in motion away from its natural place. Geocentrism created a problem for Greek astronomy. All of the motions of the heavenly bodies had to be real ones – some couldn’t be merely apparent, and due to the motion of the earth. This meant that the Greeks had to develop complex devices to generate the motions of the planets. While one can understand why the Greeks adopted geocentrism, this remained a weakness in their astronomy and cosmology.