Deity, but such a conclusion can find no support in the scientific theorem, which is simply a generalised description of phenomena. The general considerations upon which the belief in the existence and direct action of Deity are otherwise founded, are in no wise disturbed by the establishment of any such scientific theorem. The theological question is left just where it was before. We are still at perfect liberty to maintain that it is the direct action of Deity which is manifested in the planetary movements; having done nothing more with our Newtonian hypothesis than to construct a happy formula for expressing the mode or order of the manifestation. We may have learned something new concerning the manner of Divine action; we certainly have not "substituted" any other kind of action for it. And what is thus obvious in this simple astronomical example is equally true in principle in every case whatever in which one set of phenomena is interpreted by comparison with another set. In no case whatever can science use the words "force' or "cause" except as metaphorically descriptive of some observed or observable sequence of phenomena. And consequently at no imaginable future time, so long as the essential conditions of human thinking are maintained, can science even attempt to substitute the action of any other power

for the direct action of Deity. Darwinism may convince us that the existence of highly complicated organisms is the result of an infinitely diversified aggregate of circumstances so minute as severally to seem trivial or accidental; yet the consistent theist will always occupy an impregnable position in maintaining that the entire series in each and every one of its incidents is an immediate manifestation of the creative action of God.

From an obverse point of view it might be argued that since a philosophical theism must regard Divine power as the immediate source of all phenomena alike, therefore science cannot properly explain any particular group of phenomena by a direct reference to the action of Deity. Such a reference is not an explanation, since it adds nothing to our previous knowledge either of the phenomena or of the manner of Divine action. The business of science is simply to ascertain in what manner phenomena co-exist with each other or follow each other, and the only kind of explanation with which it can properly deal is that which refers one set of phenomena to another set. In pursuing this its legitimate business science does not trench on the province of theology in any way, and there is no conceivable occasion for any conflict between the two. From this and the previous

considerations taken together it follows not only that such explanations as are contained in the Newtonian and Darwinian theories are entirely consistent with theism, but also that they are the only kind of explanations with which science can properly concern itself at all. To say that complex organisms were directly created by the Deity is to make an assertion which, however true in a theistic sense, is utterly barren. It is of no profit to theism, which must be taken for granted before the assertion can be made; and it is of no profit to science, which must still ask its question, "How?"

Setting aside, then, the theological criticism as irrelevant to the question really at stake, the Darwinian theory, like the Newtonian, remains to be tested by strictly scientific considerations. In the more recent instance, as in the earlier, the relevant question is how far the course of events as sketched by the hypothesis agrees with the observed phenomena of nature. But in the directness with which this question can be answered there is great difference between the two theories. The Newtonian hypothesis asserted the existence of a general physical property of matter, and could therefore be tested by a single crucial instance, such as was afforded by the simple case of the planetary motions.

Kepler's three laws comprised in succinct form a very complete description of the movements of the planets, and when it was shown that these movements were just such as must occur according to the theory of gravitation, the theory was rightly regarded as verified. Further confirmatory instances could but repeat the same lesson, as when the irregularities of movement, due to the attractions exercised by the various planets upon each other, were likewise seen to conform strictly to the hypothesis. Nor was any alteration or enlargement of the original theory required in order to obtain the supreme triumph of verified prediction, as when Clairaut foretold the precise amount of delay in the reappearance of Halley's comet caused by the interfering attractions of Jupiter and Saturn, or as when Leverrier and Adams discovered the existence of Neptune through its effects upon the motions of Uranus. In all these cases the physical principle involved was simple, and admitted of precise mathematical treatment; and it is owing to this that the law of gravitation has become the most illustrious example which the history of science can furnish of a completely verified hypothesis.

To look for similar conciseness of verification in the case of the Darwinian theory would be to

mistake entirely the conditions under which scientific evidence can be procured. To estimate properly the value of any hypothesis it is necessary that we should know what kind and degree of proof to expect; and in the present case we must not look for a demonstration that shall be direct and simple. Instead of a universal property of matter, so conspicuous as to be recognised at once by the inspection of a few striking instances, we have in the theory of natural selection to deal with a very complex process, working results of endless diversity throughout the organic world, and often masked in its action by accompanying processes, some of which we can detect without being able to estimate their relative potency, while others no doubt have thus far escaped our attention altogether. Accordingly, while we may consider it as certain that natural selection is capable of working specific changes in organisms, we may at the same time find it impossible to give a complete account of the origin of any one particular species through natural selection, because we can never be sure that we have taken due notice of all the innumerable concrete circumstances involved in such an event. The theory, therefore, cannot be adequately tested by any single striking instance, but must depend for its support on the cumulative evidence afforded by its