THREE:Ever since the age of Parmenides and Heracleitus, Greek thought had been haunted by a pervading dualism which each system had in turn attempted to reconcile, with no better result than its reproduction under altered names. And speculation had latterly become still further perplexed by the question whether the antithetical couples supposed to divide all Nature between them could or could not be reduced to so many aspects of a single opposition. In the last chapter but one we showed that there were four such competing pairsBeing and Not-Being, the One and the Many, the Same and the Other, Rest and Motion. Plato employed his very subtlest dialectic in tracing out their connexions, readjusting their relationships, and diminishing the total number of terms which they involved. In what was probably his last great speculative effort, the Timaeus, he seems to have selected Sameness and Difference as the couple best adapted to bear the heaviest strain of thought. There is some reason for believing that in his spoken lectures he followed the Pythagorean system more closely, giving the preference to the One and the Many; or he may have employed the two expressions indifferently. The former would sooner commend itself to a dialectician, the latter to a mathematician. Aristotle was both, but he was before all things a naturalist. As such, the antithesis of Being and Not-Being, to which Plato attached little or no value, suited him best. Accordingly, he proceeds to work it out with a clearness before unknown in Greek philosophy. The first and surest of all principles, he declares, is, that a thing cannot both be and not be, in the same sense of the words, and furthermore that it must either be or not be. Subsequent340 logicians prefixed to these axioms another, declaring that whatever is is. The three together are known as the laws of Identity, Contradiction, and Excluded Middle. By all, except Hegelians, they are recognised as the highest laws of thought; and even Hegel was indebted to them, through Fichte, for the ground-plan of his entire system.235Passing from sensation to thought, it is admitted that abstract conceptions are incorporeal: how, then, can they be received and entertained by a corporeal substance? Or what possible connexion can there be between different arrangements of material particles and such notions as temperance and justice? This is already a sufficiently near approach to the language of modern philosophy. In another essay, which according to the original arrangement stands third, and must have been composed immediately after that whence the foregoing arguments are transcribed, there is more than an approach, there is complete coincidence.437 To deduce mind from atoms is, says Plotinus, if we may so speak, still more impossible than to deduce it from the elementary bodies. Granting that the atoms have a natural movement downwards, granting that they suffer a lateral deflection and so impinge on one another, still this could do no more than produce a disturbance in the bodies against which they strike. But to what atomic movement can one attribute psychic energies and affections? What sort of collision in the vertical line of descent, or in the oblique line of deflection, or in any direction you please, will account for the appearance of a particular kind of reasoning or mental impulse or thought, or how can it account for the existence of such processes at all? Here, of course, Plotinus is alluding to the Epicureans; but it is with the Stoic and other schools that he is principally concerned, and we return to his attack on their psychology.
