But the failure of psychology opens up the way to metaphysic. 'The turning-round of thought from psychology to metaphysic is the true interpretation of the Platonic conversion of the soul from ignorance to knowledge, from mere opinion to certainty and satisfaction; in other words, from a discipline in which the thinking is only apparent, to a discipline in which the thinking is real.' 'The difference is as great between "the science of the human mind" and metaphysic, as it is between the Ptolemaic and the Copernican astronomy, and it is very much of the same kind.' It is not that metaphysic proposes to do more than psychology; it aims at nothing but what it can fully overtake, and does not propose to carry a man farther than his tether extends, or the surroundings in which he finds himself. Metaphysic in the hands of all true astronomers of thought, from Plato to Hegel, if it accomplishes more, attempts less.
Metaphysic, Ferrier says, demands the whole given fact, and that fact is summed up in this: 'We apprehend the perception of an object,' and nothing short of this suffices—that is, not the perception of matter, but our apprehension of that perception, or what we before called knowledge, ultimate knowledge in its widest sense. And this given fact is unlike the mere perception of matter, for it is capable of analysis and is not simply subjective and egoistic. Psychology recognises perception on the one hand (subjective), and matter on the other (objective), but metaphysic says the distinction ought to be drawn between 'our apprehension' and 'the perception-of-matter,' the latter being one fact and indivisible, and on no account to be taken as two separate facts or thoughts. The whole point is, that by no possible means can the perception-of-matter be divided into two facts or
