And the second condition which follows from such a metaphysical principle of Ethics, is (2) that the eternal reality cannot be perfect--cannot be the sole good. For just as a reasonable rule of conduct requires that what we are told to realise should be capable of being truly real, so it requires that the realisation of this ideal shall be truly good. It is just that which _can_ be realised by our efforts--the appearance of the eternal in time, or whatsoever else is allowed to be attainable--which must be truly good, if it is to be worth our efforts. That the eternal reality is good, will by no means justify us in aiming at its manifestation, unless that manifestation itself be also good. For the manifestation is different from the reality: its difference is allowed, when we are told that it can be made to exist, whereas the reality itself exists unalterably. And the existence of this manifestation is the only thing which we can hope to effect: that also is admitted. If, therefore, the moral maxim is to be justified, it is the existence of this manifestation, as distinguished from the existence of its corresponding reality, which must be truly good. The reality may be good too: but to justify the statement that we ought to produce anything, it must be maintained, that just that thing itself, and not something else which may be like it, is truly good. If it is not true that the existence of the manifestation will add something to the sum of good in the Universe, then we have no reason to aim at making it exist; and if it is true that it will add something to the sum of good, then the existence of that which is eternal cannot be perfect by itself--it cannot include the whole of possible goods. Metaphysics, then, will have a bearing upon practical Ethics--upon the question what we ought to do--if it can tell us anything about the future consequences of our actions beyond what can be established by ordinary inductive reasoning. But the most characteristic metaphysical doctrines, those which profess to tell us not about the future but about the nature of an eternal reality, can either have no bearing upon this practical question or else must have a purely destructive bearing. For it is plain that what exists eternally cannot be affected by our actions; and only what is affected by our actions can have a bearing on their value as means. But the nature of an eternal reality either admits no inference as to the results of our actions, except in so far as it can _also_ give us information about the future (and how it can do this is not plain), or else, if, as is usual, it is maintained to be the sole reality and the sole good, it shews that no results of our actions can have any value whatever.