Passing 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. The activities of the soul are thought, sensation, reasoning, desire, attention, and so forth: the activities of body are heat, cold, impact, and gravitation; if to these we add the characteristics of mind, the latter will have no special properties by which it can be known. And even in body we distinguish between quantity and quality; the former, at most, being corporeal, and the latter not corporeal at all. Here Plotinus just touches the idealistic method of modern spiritualism, but fails to follow it any further. He seems to have adopted Aristotle’s natural realism as a sufficient theory of external perception, and to have remained uninfluenced by Plato’s distrust of sensible appearances.