From Burnet's Introduction

VI. General Characteristcs of Greek Cosmology
The Ionians, as we can see from their literature, were deeply impressed by the transitoriness of things. There is, in fact, a fundamental pessimism in their outlook on life, such as is natural to an over-civilised age with no very definite religious convictions. We find Mimnermos of Kolophon preoccupied with the sadness of the coming of old age, while at a later date the lament of Simonides, that the generations of men fall like the leaves of the forest, touches a chord that Homer had already struck.¹⁶ Now this sentiment always finds its best illustrations in the changes of the seasons, and the cycle of growth and decay is a far more striking phenomenon in Aegean lands than in the North, and takes still more clearly the form of a war of opposites, hot and cold, wet and dry. It is, accordingly, from that point of view the early cosmologists regard the world. The opposition of day and night, summer and winter, with their suggestive parallelism in sleep and waking, birth and death, are the outstanding features of the world as they saw it.¹⁷

The changes of the seasons are plainly brought about by the encroachments of one pair of opposites, the cold and the wet, on the other pair, the hot and the dry, which in their turn encroach on the other pair. This process was naturally described in terms borrowed from human society; for in early days the regularity and constancy of human life was far more clearly realised than the uniformity of nature. Man lived in a charmed circle of social law and custom, but the world around him at first seemed lawless. That is why the encroachment of one opposite on another was spoken of as injustice (ἀδικία) and the due observance of a balance between them as justice (δίκη). The later word κόσμος is based on this notion too. It meant originally the discipline of an army, and next the ordered constitution of a state.

That, however, was not enough. The earliest cosmologists could find no satisfaction in the view of the world as a perpetual contest between opposites. They felt that these must somehow have a common ground, from which they had issued and to which they must return once more. They were in search of something more primary than the opposites, something which persisted through all change, and ceased to exist in one form only to reappear in another. That this was really the spirit in which they entered on their quest is shown by the fact that they spoke of this something as "ageless" and "deathless."¹⁸ If, as is sometimes held, their real interest had been in the process of growth and becoming, they would hardly have applied epithets so charged with poetical emotion and association to what is alone permanent in a world of change and decay. That is the true meaning of Ionian "Monism."¹⁹

16. See Butcher, "The Melancholy of the Greeks," in Some Aspects of the Greek Genius, pp. 130 sqq.

17. This is well brought out by Prof. J. L. Myres in a paper entitled "The Background of Greek Science" (University of Chicago Chronicle, vol. xvi. No. 4). There is no need to derive the doctrine of the "opposites" from a "religious representation" as Mr. Cornford does in the first chapter of From Religion to Philosophy. In Greece these force themselves upon our attention quite apart from anything of the sort. Of course they are also, important in agrarian magic for practical reasons.

18. Ar. Phys. Γ, 4. 203 b 14 ἀθάνατον γὰρ καὶ ἀνώλεθρον (sc. τὸ ἄπειρον), ὥς φησιν Ἀναξίμανδρος καὶ οἱ πλεῖστοι τῶν φυσιολόγων Hipp. Ref. i. 6, 1 φύσιν τινὰ τοῦ ἀπείρου . . . ταύτην δ' ἀίδιον εἶναι καὶ ἀγήρω. The epithets come from the Epic, where ἀθάνατος καὶ ἀγήρως is a standing phrase to mark the difference between gods and men.

19. As it has been suggested that the Monism ascribed by later writers to the early cosmologists is only based on Aristotle's distinction between those who postulated one ἀρχή and those who postulated more than one (Phys. A, 2. 184 b 15 sqq.), and is not therefore strictly historical, it will be well to quote a pre-Aristotelian testimony for it. In the Hippokratean Περὶ φύσιος ἀνθρώπου (Littré, vi. 32) we read φασί τε γὰρ ἕν τι εἶναι ὅτι ἔστι, καὶ τοῦτ' εἶναι τὸ ἕν καὶ τὸ πᾶν, κατὰ δὲ τὰ ὀνόματα οὐκ ὁμολογέουσι· λέγει δ' αὐτῶν ὁ μέν τις φάσκων ἀέρα εἶναι τοῦτο τὸ ἓν καὶ τὸ πᾶν, ὁ δὲ πῦρ, ὁ δὲ ὕδωρ, ὁ δὲ γῆν, καὶ ἐπιλέγει ἕκαστος τῷ ἑωυτοῦ λόγῳ μαρτύριά τε καὶ τεκμήρια ἅ γε ἔστιν οὐδέν.