Two centuries or more later, in the sixth century BC, the first Greek philosophers speculated, without invoking mythology, on how the world was generated. They regarded the world as being based on a single live space-filling substance from which all things developed spontaneously by the interplay of opposed processes such as separation and combination or rarefaction and condensation. The first explicit statement in Greek literature that, although individual things are subject to change and decay, the world itself is eternal appears to have been made by the philosopher Heraclitus about 500 BC. He regarded perpetual change as the fundamental law governing all things--a view which is summarized in his famous aphorism, 'You cannot step twice into the same river'. He also believed that there is a perpetual strife of opposites: hot and cold, wet and dry, and so on, are each necessary complements to the other and their eternal conflict is the very basis of existence. This world of change and conflict, however, is not just a chaos but is governed throughout time by a principle of order or balance of opposites, keeping them within their due bounds.
This principle was based on an idea that was accepted by other Greek thinkers of this period--the concept of Time as a judge. For example, Anaximander, in the only surviving fragment directly attributed to him, said that all things that are created must also perish, making atonement to one another for their injustice according to Time's decree. This idea was no doubt suggested by the cycle of the seasons with its alternating conflict of the hot and the cold, the wet and the dry. Each of these advances in 'unjust' aggression at the expense of its opposite and then pays the penalty, retreating before the counter-attack of the latter, the object of the whole cycle being to maintain the balance of justice. The fundamental assumption was that Time will always discover and avenge any act of injustice.
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The concept of Time as a judge can also be attributed to the great Athenian statesman Solon ( sixth century BC) who, according to Werner Jaeger, 'defends himself "before the bench of Time"'. (In this context it may be mentioned that in Athenian law courts it became the custom to have a clepsydra to ensure that most speeches were limited to half an hour.) This was an age when the state was being founded on the concept of justice. The original Greek word for justice', themis, signified 'divine law'. Although in the Iliad the word dikē denotes a judgement given by a judge or an assertion by a party to a dispute of his rights, in the Odyssey it signifies 'right' or 'custom'.4 Later it became the slogan of those struggling for equal justice for all. Anaximander and Heraclitus extended the concept of justice to the whole universe:
In the life of politics the Greek language refers to the reign of justice by the term kosmos; but the life of nature is a kosmos too, and indeed this cosmic view of the universe begins with Anaximander's dictum. To him everything that happens in the natural world is rational through and through and subject to a rigid norm.5
Emphasis on the role of time characterized the Pythagorean idea of the kosmos. According to Plutarch, when asked what Time ( Chronos) was, Pythagoras ( sixth century BC) replied that it was the 'soul', or procreative element, of the universe. The extent to which Pythagoras and his followers may have been influenced by oriental ideas has long been a subject for argument. The Orphic idea of Chronos, which may have had an influence on Pythagoras, seems rather like the Iranian idea of Zurvan akarana. In particular, both were depicted as multi-headed winged serpents. Similarly, the dualism which played an important role in Pythagorean philosophy appears to echo the Zoroastrian cosmic opposition of Ohrmazd and Ahriman, although these two ultimates were regarded as personal gods and not as abstract principles like the Pythagorean ten basic pairs of opposites, such as limit versus unlimited, good versus bad, male versus female, odd versus even. The most fruitful feature of Pythagorean teaching was the key idea that the essence of things is to be found in the concept of number, which was regarded as having spatial and also temporal significance. Numbers were represented figuratively by patterns similar to those still found on dominoes and dice. Although this led to Greek mathematics being dominated by geometry, time was no less an important element in early Pythagorean thought. Indeed, even spatial configurations were regarded as temporal by nature,
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as is indicated by the role of the gnomon. This was originally a time- measuring instrument--a simple upright sundial. Later the same term was used to denote the geometrical figure that is formed when a smaller square is cut out of a larger square with two of its adjacent sides lying along two adjacent sides of the latter. Eventually, the term came to denote any number which, when added to a figurate number, generates the next higher number of the same shape (triangular numbers, square numbers, pentagonal numbers, and so on). The generation of numbers was regarded by the early Pythagoreans as an actual physical operation occurring in space and time, and the basic cosmogonical process was identified with the generation of numbers from the initial unit, the Monad, which may have been a sophisticated version of the earlier Orphic idea of the primeval World-egg.
It is well known that Pythagoras' belief in the significance of numbers was supported by his alleged discovery, with the aid of a stringed instrument, that the concordant intervals of the musical scale correspond to simple numerical ratios. This led many later Greek thinkers to regard musical theory as a branch of mathematics (together with geometry, arithmetic, and astronomy it constituted what eventually came to be called the quadrivium), although this view was not universally accepted, the most influential of those who rejected it being Aristoxenus of Tarentum ( fourth century BC). He emphasized, instead, the role of sensory experience. For him the criterion of musical phenomena was not mathematics but the ear.
Long before the time of Aristoxenus, some of the most acute Greek thinkers had found that the concept of time was difficult to reconcile with their idea of rationality. Indeed, Parmenides, the founding father of logical disputation, argued that time cannot pertain to anything that is truly real. The essence of his difficulty was that time and change imply that the same thing can have contradictory properties--it can be, say, hot and cold, depending on the time--and this conflicted with the rule that nothing can possess incompatible attributes. His basic proposition was 'That which is is, and it is impossible for it not to be.' From this he argued that, since only the present 'is', it follows that past and future are alike meaningless, the only time is a continual present time and what exists is both uncreated and imperishable. Parmenides drew a fundamental distinction between the world of appearance, characterized by time and change, and the world of reality which is unchanging and timeless. The former is revealed to us by our senses, but these are
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deceptive. The latter is revealed to us by reason and is the only true mode of existence.
The difficulties involved in producing a logically satisfactory theory of time were emphasized by Parmenides' follower Zeno of Elea in his subtle paradoxes concerning motion. The most famous is the one generally known as the paradox of 'Achilles and the tortoise'. (The identification of Achilles' competitor as a tortoise is due to later commentators.) The tortoise is given an initial lead over Achilles, and the argument asserts that however fast Achilles runs he will never reach the tortoise. For, when Achilles reaches the point from which the tortoise starts, the tortoise will have advanced to a farther point. When Achilles reaches that point, the tortoise will be at a still farther point, and so on ad infinitum. Consequently, as Aristotle puts it in his account, 'the slower will always have a lead', in contradiction with experience, that is, the world of appearance. This argument assumes that space and time are infinitely divisible, but not all of Zeno's arguments involve this assumption. The problems that his paradoxes raise concerning the mathematical structure of space and time are still being discussed today.6
The difficulties discussed by Parmenides and Zeno do not occur if the concept of time is rejected as 'unreal'. Their influence on Plato ( 427-347 BC) is evident in the different treatment of space and time in his cosmological dialogue the T
imaeus. Space exists in its own right as a given frame for the visible order of things, whereas time is simply a feature of that order. In Plato's cosmology the universe was fashioned by a divine artificer imposing form and order on primeval matter, which was originally in a state of chaos. This divine artificer was, in effect, the principle of reason, which by imposing order on chaos reduced it to the rule of law. The pattern of law was provided by an ideal realm of geometrical shapes which were eternal and in a perfect state of absolute rest, like the real world of Parmenides. Unlike the eternal ideal model on which it is based, the universe is subject to change. Time is that aspect of change which bridges the gap between the universe and its model, being 'a moving image of eternity'. This moving image manifests itself in the motions of the heavenly bodies. Plato's intimate association of time and the universe led him to regard time as being actually produced by the revolutions of the celestial sphere. A permanent legacy of his theory of time is the idea that time and the universe are inseparable. In other words, time does not exist in its own right but is a characteristic of the universe.
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Plato's conclusion that time is actually produced by the universe was not accepted by Aristotle ( 384-322 BC), who rejected the idea that time can be identified with any form of motion or change. For, he argued, motion can be uniform or non-uniform and these terms are themselves defined by time, whereas time cannot be defined by itself. Nevertheless, although time is not identical with motion or change, it seemed to be dependent on them. He remarks that when the state of our minds does not appear to change we do not notice that time has elapsed. It is by being aware of 'before' and 'after' in change that we are aware of time. He came to the conclusion that time can be regarded as a numbering process associated with our perception of 'before' and 'after' in motion and change. He realized that the relation between time and change is a reciprocal one: without change time could not be recognized, whereas without time change could not occur. 'Not only do we measure the movement by the time, but also the time by the movement, because they define each other. The time marks the movement, since it is its number, and the movement the time' ( Physica, iv. 220b). Aristotle recognized that movement can cease whereas time cannot, but there is one motion that continues unceasingly, namely that of the heavens. Clearly, although he did not agree with Plato, he too was profoundly influenced by the cosmological view of time. He rejected the identification of time with the circular motion of the heavens, but he regarded the latter as the perfect example of uniform motion. Consequently, it provides the perfect measure of time.
Although for Aristotle physics meant the study of motion and change in nature, the main emphasis was placed by him on the states between which change takes place rather than on the actual course of the motion itself. Thus the static form rather than the dynamic process became the characteristic concept in his philosophy of nature, and form and place were more fundamental than time. His natural philosophy was dominated by the idea of the permanence of the cosmos. He rejected all evolutionary theories and stressed instead the essentially cyclical nature of change.
Belief in the cyclical nature of the universe found its apotheosis in the concept of the Great Year, which the Greeks may have inherited from the Babylonians. The idea had two distinct interpretations. On the one hand, it was simply the period required for the sun, moon, and planets to attain the same positions in relation to each other as they had at a given time. This appears to be the sense in which Plato used the idea in the Timaeus. On the other hand, for Heraclitus it signified the period of the
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world from its formation to its destruction and rebirth. According to him the universe sprang from fire and will end in fire. This idea was probably transmitted from Iran, where it originated. The two interpretations were combined in late antiquity by the Stoics, who believed that, when the heavenly bodies return at fixed intervals of time to the same relative positions as they had at the beginning of the world, everything would be restored just as it was before and the entire cycle would be renewed in every detail. As Nemesius, Bishop of Emesa in the fourth century AD, later put it:
Socrates and Plato and each individual man will live again, with the same friends and fellow citizens. They will go through the same experiences and the same activities. Every city and village and field will be restored, just as it was. And this restoration of the universe takes place not once, but over and over again--indeed to all eternity without end. Those of the gods who are not subject to destruction, having observed the course of one period, know from this everything which is going to happen in all subsequent periods. For there will never be any new thing other than that which has been before, but everything is repeated down to the minutest detail.7
Nevertheless, as Ludwig Edelstein has pointed out, even in late antiquity there were philosophers, as well as historians and scientists, who regarded time as non-cyclical.8 Cosmological recurrence involving the complete destruction of the universe and its exact re-creation, as believed in by the Stoic philosophers, must be distinguished from historical recurrence involving only the repetition of the general pattern of events, as believed in by the historian Polybius, for example.
Greek civilization not only gave rise to philosophy but it also produced, in the fifth century BC, the first real historians. Until then the Greeks believed that recent events were unimportant compared with the exploits of the heroes in Trojan times. Historiography arose when an event occurred which in its magnitude matched the greatest events celebrated in legend. The whole complex of events in the Persian wars from the fall of Sardis to the retreat of Xerxes was seen as a unity and formed what Robert Drews has called 'one Great Event of awesome proportions'.9 Originally, the Greek historian's task was not to explain the present in terms of the past but to ensure that significant actions and events would not be forgotten in the future. Consequently, in its origins Greek historiography was more closely affiliated to epic poetry than to philosophy, and in its development it retained a commemorative function. Greek historians, for example Thucydides, tended to
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concentrate on the recent past, their object being to put in writing those significant actions which were remembered but had not yet been recorded.
The difficulties against which the 'fathers of history', Herodotus and Thucydides, had to contend were formidable. The Greeks of their time knew astonishingly little about their own past. Not only had they no documents going back more than a century or two, but much of what they 'knew' was merely myth and legend. Since their interest in the past was primarily moralistic, precise knowledge of actual events and when they happened was not required. Herodotus was able to establish some kind of time-sequence for the two centuries before his time, but he was a more diffuse writer than Thucydides, who was concerned with many events occurring in a shorter time interval. As Sir Moses Finley has pointed out, Thucydides, in writing about the Peloponnesian war ( History of the Peloponnesian War, ii. 1), actually had to invent an appropriate system of dating, since each Greek city had its own calendar. In his time the year was usually indicated by the name of an official, for example at Athens the first archon and at Sparta the first ephor. Thucydides fixed the beginning of the war and dated subsequent events by counting how many years had elapsed from the start. Each year of the war he divided into two, which he called summer and winter, respectively. 'Simple enough,' Finley comments, 'yet the scheme was unique and the difficulties in making it work are nearly unimaginable today.'10
Whereas Herodotus transformed 'history' (historia) from a general enquiry about the world into an enquiry about past events, Thucydides believed that serious history could be concerned only with the present, or the immediate past. Although he did not succeed in imposing his strict standards of reliability on later Greek historians, he effectively discouraged the idea that one could do genuine historical research about the past.11 Nevertheless, by the latter part of the fifth century BC there was a greater general awareness of the significance of time than
there had been previously. Although Homer dealt with allegedly historical subjects, his was 'aristocratic' history, involving no chronology, no temporal continuity with later ages, and no real sense of the passage of time. For example, despite Odysseus' twenty years' absence from home, on his return neither he nor Penelope appear to have grown any older. In short, for Homer it made no difference that year follows year. On the other hand, by the time of Herodotus and Thucydides life in the polis did not consist of isolated episodes covering heroes but depended on the
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continuity of institutions, laws, contracts, and expectations. The passage of time had become more relevant.
In particular, problems of the calendar were the driving force that led to the initial development of Greek mathematical astronomy in the last decades of the fifth century BC. Most Greek religious festivals occurred at or near full moon, but since they were associated with agricultural activities they had to take place at the appropriate times of the year. It therefore became necessary to adopt a luni-solar calendar in which the months were measured by the phases of the moon but which also kept in step with the sun. Since the length of the lunar month is about twenty- nine and a half days and a calendar month cannot contain a fractional part of a day, it was arranged that the calendar months were alternately of twenty-nine and thirty days. As in Babylonia, this calendar was adapted to the sun by intercalating a thirteenth month from time to time, but this was left to local officials in the different cities to decide, and they did this individually and arbitrarily. Astronomers, on the other hand, sought to introduce a regular intercalation by means of a cycle of fixed period. According to Geminus, the author of a manual of astronomy of about 70 BC, the first such cycle obtained by the Greeks was an eight-year solar cycle containing ninety-nine months (three of which were intercalary), but there is considerable doubt about the origin of this cycle, known as the 'octaeteris'. The first well-attested cycle of this type was introduced in 432 BC by Meton. As previously mentioned (ch. 3), it was a nineteen- year solar cycle of 235 months (see Appendix 2). Astronomically based cycles such as the Metonic were used, however, only in scientific texts and had no influence on the various local civil calendars. Meton lived in Athens and appears as a character ridiculed by Aristophanes in The Birds, produced in 414 BC.
Time in History: Views of Time From Prehistory to the Present Day Page 6