Plato applies the theory of degradation in his study of political communities. [Footnote: Plato's philosophy of history. In the myth of the Statesman and the last Books of the Republic. The best elucidation of these difficult passages will be found in the notes and appendix to Book viii. in J. Adam's edition of the Republic (1902).] He conceives his own Utopian aristocracy as having existed somewhere towards the beginning of the period of the world's relapse, when things were not so bad, [Footnote: Similarly he places the ideal society which he describes in the Critias 9000 years before Solon. The state which he plans in the Laws is indeed imagined as a practicable project in his own day, but then it is only a second-best. The ideal state of which Aristotle sketched an outline (Politics, iv. v.) is not set either in time or in place.] and exhibits its gradual deterioration, through the successive stages of timocracy, oligarchy, democracy, and despotism. He explains this deterioration as primarily caused by a degeneration of the race, due to laxity and errors in the State regulation of marriages, and the consequent birth of biologically inferior individuals. 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.