Aet. v. 30, 1, Ἀλκμαίων τῆς μὲν ὑγιείας εἶναι συνεκτικὴν τὴν ἰσονομίαν τῶν δυνάμεων, ὑγροῦ, ξηροῦ, ψυχροῦ, θερμοῦ, πικροῦ, γλυκέος, καὶ τῶν λοιπῶν, τὴν δ’ ἐν αὐτοῖς μοναρχίαν νόσου ποιητικήν· φθοροποιὸν γὰρ ἐκατέρου μοναρχίαν. Footnote 500: My colleague, Dr. Fraser Harris, points out to me that Alkmaion’s πόροι may have been a better guess than he knew. The nerve-fibres, when magnified 1000 diameters, “sometimes appear to have a clear centre, as if the fibrils were tubular.”—Schäfer, _Essentials of Physiology_ (7th edition), p. 132. CHAPTER V EMPEDOKLES OF AKRAGAS [Sidenote: Pluralism.] 97. The belief that all things are one was common to the philosophers we have hitherto studied; but now Parmenides has shown that, if this one thing really _is_, we must give up the idea that it can take different forms. The senses, which present to us a world of change and multiplicity, are deceitful. From this there was no escape; the time was still to come when men would seek the unity of the world in something which, from its very nature, the senses could never perceive. We find, accordingly, that from the time of Parmenides to that of Plato, all thinkers in whose hands philosophy made real progress abandoned the monistic hypothesis. Those who still held by it adopted a critical attitude, and confined themselves to a defence of the theory of Parmenides against the new views. Others taught the doctrine of Herakleitos in an exaggerated form; some continued to expound the systems of the early Milesians. This, of course, showed want of insight; but even those thinkers who saw that Parmenides could not be left unanswered, were by no means equal to their predecessors in power and thoroughness. The corporealist hypothesis had proved itself unable to bear the weight of a monistic structure; but a thorough-going pluralism such as the atomic theory might have some value, if not as a final explanation of the world, yet at least as an intelligible view of a part of it. Any pluralism, on the other hand, which, like that of Empedokles and Anaxagoras, stops short of the atoms, will achieve no permanent result, however many may be the brilliant _aperçus_ which it embodies. It will remain an attempt to reconcile two things that cannot be reconciled, and may always, therefore, be developed into contradictions and paradoxes. [Sidenote: Date of Empedokles.]