It was no doubt the vague feeling of these perplexities that forced John Stuart Mill, the most eminent defender of this school of thought, to denominate matter a Permanent Possibility of Sensation. This singular phrase well exemplifies the difficulties of his position. For is matter an external substance, existing independently, or not? If it is, then what becomes of the Berkeleyan doctrine? Mill and his followers are simply metaphysical Realists. But if not, what becomes of the permanence? It is not in us, for our sensations are not permanent; it is not in the matter, for there is none. And what is there a possibility of? Causing sensation, or having it? Not the former, for there is nothing to cause it; not the latter, for the possibility of our having sensations is a mere fact of our nature, and cannot serve to define matter. And where is the sensation located? The phraseology would seem to imply, that matter is in the permanent condition of possible feeling; just as the nerve may be in the permanent condition of possible excitation. But this would be placing sensation in the wrong quarter. And if sensation be in us, we have not a permanent possibility, but a permanent actuality of sensation. So that unless the words be construed to mean that there is outside of us a permanent something which excites sensation, of which the modes vary (for this is the sense of possibility), they have no assignable meaning whatever. Mill, in fact, had been compelled, without wishing it, to recognize an ultimate power in nature; and his perception of this truth conflicted strangely, in his candid mind, with his idealistic prepossessions.

A more consistent and rigorous form of Idealism is that which has been referred to as the strict consequence of Moderate Idealism. This form, which I will term Extreme Idealism, denies the existence of persons as well as things. The Extreme Idealist believes himself to be the only being in the universe. There is to him no period preceding his own existence; none succeeding it. Past and future, except in his own life, have no meaning for him. We cannot reason with him, for all we may say is only a transient mode of his own sensations. Obviously, to such a philosophy there is no reply but one: it is simply unthinkable. Were any one seriously to defend it, the very seriousness of his defense would prove that he did not believe it. For against what or whom would he be contending? Against a phantom of his own mind. And the more pains he took to prove to us that he believed us to have no existence but as a part of himself, the less credit should we attach to his assertions.

Philosophy, therefore, is under a logical compulsion to make the same fundamental assumption as Religion—that of an ultimate, unknown, and all-pervading Power Origin, or Cause. Science, in a variety of ways, does the same. It does so, first, in its belief of a past and a future in the history of the solar system far transcending the past and future of humanity, or indeed of any form of life whatever. Passing at a glance over our brief abode on the face of the earth, Geology pushes its researches back into a time preceding by innumerable ages the existence of mankind, while her elder sister Astronomy carries her vision to a still remoter age, when even the planet we now inhabit was but a fragment in one indistinguishable mass. But it is not only these two sciences that assume the continuance of nature quite independently of our presence or absence; every other science does the like. The botanist, the chemist, the physicist, all believe that the facts they assert are facts in an external nature, the relations of which as now discovered by their several sciences held good before man existed, and will hold good after he has ceased to exist. But to say this, is to say in effect that there is something more than the mere phenomena disclosed by investigation; namely, an external reality persisting through all time in which the varied series of phenomena take their rise.

More clearly still does Science assert some such reality in its great modern doctrine of the Persistence of Force. Not that this doctrine is entirely new; for regarded in its metaphysical rather than its physical aspect it is but an expression in the language of the day of a truth which has long been realized as a necessity of thought. It is the converse of the ancient axiom, "Nihil ex nihilo fit," for if nothing can be made from nothing, neither can something pass into nothing. The Persistence of Force is an expression of the fact that every cause must have an adequate effect; that in nature nothing can be lost, no particle of force pass into nonentity. Concentrated forces may be dissipated, and dissipated forces may be concentrated; or one variety of force may pass into another. But the ultimate fund of force remains ever unchangeable; nothing is ever created, nothing destroyed.

Observe, then, that Science, however cautiously it may keep within the range of the material world, however eagerly it may repudiate all investigation of ultimate causes as fruitless and unprofitable, cannot take one single step towards proving the propositions it advances without tacitly laying down an ontological entity as the basis of its demonstration. For to speak of its discoveries as laws of nature is simply to predicate a constant, unvarying force, which under like conditions always produces like results. And to declare the uniformity of nature, is merely to say that the methods of that force do not change—that it is the same now as it ever was, and will be the same throughout the eternal ages.

"Thus," writes Mr. Herbert Spencer, "by the Persistence of Force, we really mean the persistence of some Power which transcends our knowledge and conception. The manifestations, as occurring in ourselves or outside of us, do not persist; but that which persists is the Unknown Cause of these manifestations. In other words, asserting the Persistence of Force, is but another mode of asserting an Unconditional Reality, without beginning or end" (Spencer's "First Principles," § 60, p. 189).

Philosophy, or Reasoned Thought, and Science, or Reasoned Observation, have both led us to admit, as a fundamental principle, the necessary existence of an unknown, inconceivable, and omnipresent Power, whose operations are ever in progress before our eyes, but whose nature is, and can never cease to be, an impenetrable mystery. And this is the cardinal truth of all religion. From all sides then, by every mode of contemplation, we are forced upon the same irresistible conclusion. The final question still remains, Is this ultimate element of all religion "the correlative of any actual truth or not?"

But for the prevalence, in recent times, of a philosophy which denies all connection between the necessity of a belief and its truth, I should have regarded such a question as scarcely worth the answering. To say that a belief is necessary and to say that it is true, would appear to all, but adherents of the extreme experiential school, one and the same thing. But in the present day this cannot be taken for granted, and I should be the last to complain that even that which seems most obvious should be tested by adverse criticism.

Ingenious, however, as their arguments are, philosophers of this school, when driven to reason out their views, cut their own throats. They commit a logical suicide. For what is the test of truth they hold up to us in lieu of necessity? Experience. But what in the last resort does our belief in experience rest upon? Simply upon a mental necessity. Nobody can tell us why he believes that the laws of nature will hold good to-morrow as they do to-day. He can indeed tell us that he has always found them constant before, and therefore expects them to remain so. But this is merely to state the belief, not to justify it. Experience itself cannot be appealed to, to support our confidence in experience. True, we habitually say that we believe such and such results will follow such and such antecedents because we have always found them follow before. But our past experience is not the whole of the fact involved in the belief. It is our past experience, conjoined with the mental necessity of thinking that the future will resemble the past, that forms the convictions on which we act. Experience alone, without that mental necessity, could teach us nothing. If therefore our necessary beliefs need not be true, the belief in experience falls to the ground along with the rest, and experience cannot be put in place of necessity as a test of truth. In fact, every argument drawn from the past fallibility of the test of necessity might be retorted with tenfold force against the test of experience. Observation has constantly misled mankind, and thousands of alleged facts, accepted upon imagined experience, have been disproved by more accurate examination. Observation and reasoning combined (as they often are) are exposed to the double danger of false premises and false inferences from true premises; while the addition of an element of testimony (a circumstance common in scientific inquiries) exposes every conclusion to a threefold possibility of error. Human beings are no more exempt from the possibility of mistaken science than from that of hasty metaphysics. But as, in matters of physical research, we do not discredit the use of our eyes because their perceptions are sometimes inaccurate, so in matters of metaphysical inquiry we need not discredit the use of our minds because their apparent intuitions are now and then fallacious. In the one case, as in the other, the proper course is not to cast contempt upon the only instruments of discovery we have, but to apply those instruments again and again, omitting no precaution that may serve to correct an observation and to test an argument. But when we have done our utmost to attain whatever certainty the nature of the subject permits, we cannot reasonably turn round upon ourselves and say: "True, my eyes assure me of this fact, but human eyes have erred so often that I cannot accept their verdict;" or, "No doubt my mind forces this conclusion upon me as a necessity of thought, but so many assumed necessities have turned out not to be necessary at all that I must refuse to listen to my mind:" for this is not really the caution of science, but the rashness of philosophic theory. For we can have no higher conviction than that arising in a necessity of thought. Nothing can surpass the certainty of this. Grant that we may yet be wrong: we can never know it, and we can have no reason to think it. To oppose to a necessary belief such a train of reasoning as this: