The theories of Plato are only the most illustrious example of the tendency characteristic of Greek philosophical thinkers to idealise the immutable as possessing a higher value than that which varies.  This affected all their social speculations.  They believed in the ideal of an absolute order in society, from which, when it is once established, any deviation must be for the worse.  Aristotle, considering the subject from a practical point of view, laid down that changes in an established social order are undesirable, and should be as few and slight as possible. [Footnote:  Politics, ii. 5.] This prejudice against change excluded the apprehension of civilisation as a progressive movement.  It did not occur to Plato or any one else that a perfect order might be attainable by a long series of changes and adaptations.  Such an order, being an embodiment of reason, could be created only by a deliberate and immediate act of a planning mind.  It might be devised by the wisdom of a philosopher or revealed by the Deity.  Hence the salvation of a community must lie in preserving intact, so far as possible, the institutions imposed by the enlightened lawgiver, since change meant corruption and disaster.  These a priori principles account for the admiration of the Spartan state entertained by many Greek philosophers, because it was supposed to have preserved unchanged for an unusually long period a system established by an inspired legislator.

2.

Thus time was regarded as the enemy of humanity.  Horace’s verse,

  Damnosa quid non imminuit dies?

“time depreciates the value of the world,” expresses the pessimistic axiom accepted in most systems of ancient thought.

The theory of world-cycles was so widely current that it may almost be described as the orthodox theory of cosmic time among the Greeks, and it passed from them to the Romans.

[Footnote:  Plato’s world-cycle.  I have omitted details not essential; e.g. that in the first period men were born from the earth and only in the second propagated themselves.  The period of 36,000 years, known as the Great Platonic Year, was probably a Babylonian astronomical period, and was in any case based on the Babylonian sexagesimal system and connected with the solar year conceived as consisting of 360 days.  Heraclitus seems to have accepted it as the duration of the world between his periodic universal conflagrations.  Plato derived the number from predecessors, but based it on operations with the numbers 3, 4, 5, the length of the sides of the Pythagorean right-angled triangle.  The Great Year of the Pythagorean Philolaus seems to have been different, and that of the Stoics was much longer (6,570,000 years).

I may refer here to Tacitus, Dialogus c. 16, as an appreciation of historical perspective unusual in ancient writers:  “The four hundred years which separate us from the ancients are almost a vanishing quantity if you compare them with the duration of the ages.”  See the whole passage, where the Magnus Annus of 12,954 years is referred to.]