suppose that Ends operate in Nature, and is ideality, in any other sense, a working force there? How far such a point of view may be permitted in aesthetics or in the philosophy of religion, I shall not enquire. But considering the physical world as a mere system of appearances in space, are we on metaphysical grounds to urge the insufficiency of the mechanical view? In what form (if in any) are we to advocate a philosophy of Nature? On this difficult subject I will very briefly remark in passing.
The mechanical view plainly is absurd as a full statement of truth. Nature so regarded has not ceased at all (we may say) to be ideal, but its ideality throughout falls somewhere outside itself (Chapters xxii. and xxiii.). And that even for working purposes this view can everywhere be rigidly maintained, I am unable to assert. But upon one subject I have no doubts. Every special science must be left at liberty to follow its own methods, and, if the natural sciences reject every way of explanation which is not mechanical, that is not the affair of metaphysics. For myself, in other ways ignorant, I venture to assume that these sciences understand their own business. But where, quite beyond the scope of any special science, assertions are made, the metaphysician may protest. He may insist that abstractions are not realities, and that working fictions are never more than useful fragments of truth. And on another point also he may claim a hearing. To adopt one sole principle of valid explanation, and to urge that, if phenomena are to be explicable, they must be explained by one method—this is of course competent to any science. But it is another thing to proclaim phenomena as already explained, or as explicable, where in certain aspects or in certain provinces they clearly are not explained, and where, perhaps, not even the first beginning of an explanation has been made. In these lapses or excursions beyond its own limits
