It is the more necessary to insist on this, because the division between thought and matter, which is admitted by these writers, is often grasped at by their opponents, as a means of warding off the results which they draw from the theory of evolution. When science breaks its sword, religion assails it, with the fragment. It is not at once evident that if this chasm were shown to exist, knowledge would be a chimera; for there would be no outer world at all, not even a phenomenal one, to supply an object for it. We must postulate the ultimate unity of all beings with each other and with the mind that knows them, just because we are intellectual and moral beings; and to destroy this unity is to "kill reason itself, as it were, in the eye," as Milton said.

Now, evolution not only postulates unity, or the unbroken continuity of all existence, but it also negates all differences, except those which are expressions of that unity. It is not the mere assertion of a substratum under qualities; but it implies that the substratum penetrates into the qualities, and manifests itself in them. That which develops—be it plant, child, or biological kingdom—is, at every stage from lowest to highest, a concrete unity of all its differences; and in the whole history of its process its actual content is always the same. The environment of the plant evokes that content, but it adds nothing to it. No addition of anything absolutely new, no external aggregation, no insertion of anything alien into a growing thing, is possible. What it is now, it was in the beginning; and what it will be, it is now. Granting the hypothesis of evolution, there can be no quarrel with the view that the crude beginnings of things, matter in its most nebulous state, contains potentially all the rich variety of both natural and spiritual life.

But this continuity of all existence may be interpreted in two very different ways. It may lead us either to radically change our notions of mind and its activities, or "to radically change our notions of matter." We may take as the principle of explanation, either the beginning, or the end of the process of development. We may say of the simple and crass, "There is all that your rich universe really means"; or we may say of the spiritual activities of man, "This is what your crude beginning really was." We may explain the complex by the simple, or the simple by the complex. We may analyze the highest back into the lowest, or we may follow the lowest, by a process of synthesis, up to the highest.

And one of the most important of all questions for morality and religion is the question, which of these two methods is valid. If out of crass matter is evolved all animal and spiritual life, does that prove life to be nothing but matter; or does it not rather show that what we, in our ignorance, took to be mere matter was really something much greater? If "crass matter" contains all this promise and potency, by what right do we still call it "crass"? It is manifestly impossible to treat the potencies, assumed to lie in a thing that grows, as if they were of no significance; first, to assert that such potencies exist, in saying that the object develops; and then, to neglect them, and to regard the effect as constituted merely of its simplest elements. Either these potencies are not in the object, or else the object has in it, and is, at the first, more than it appears to be. Either the object does not grow, or the lowest stage of its being is no explanation of its true nature.

If we wish to know what the forms of natural life mean, we look in vain to their primary state. We must watch the evolution and revelation of the secret hid in natural life, as it moves through the ascending cycles of the biological kingdom. The idea of evolution, when it is not muddled, is synthetic—not analytic; it explains the simplest in the light of the complex, the beginning in the light of the end, and not vice versa. In a word, it follows the ways of nature, the footsteps of fact, instead of inventing a wilful backward path of its own. And nature explains by gradually expanding. If we hearken to nature, and not to the voice of illusory preconceptions, we shall hear her proclaim at the last stage, "Here is the meaning of the seedling. Now it is clear what it really was; for the power which lay dormant has pushed itself into light, through bud and flower and leaf and fruit." The reality of a growing thing is its highest form of being. The last explains the first, but not the first the last. The first is abstract, incomplete, not yet actual, but mere potency; and we could never know even the potency, except in the light of its own actualization.

From this correction of the abstract view of development momentous consequences follow. If the universe is, as science pronounces, an organic totality, which is ever converting its promise and potency into actuality, then we must add that the ultimate interpretation even of the lowest existence in the world cannot be given except on principles which are adequate to explain the highest. We must "level up and not level down": we must not only deny that matter can explain spirit, but we must say that even matter itself cannot be fully understood, except as an element in a spiritual world."A

A: Professor Caird, The Critical Philosophy of Kant, p. 35.

That the idea of evolution, even when applied in this consistent way, has difficulties of its own, it is scarcely necessary to say. But there is nothing in it which imperils the ethical and religious interests of humanity, or tends to reduce man into a natural phenomenon. Instead of degrading man, it lifts nature into a manifestation of spirit. If it were established, if every link of the endless chain were discovered and the continuity of existence were irrefragably proved, science would not overthrow idealism, but it would rather vindicate it. It would justify in detail the attempt of poetry and religion and philosophy, to interpret all being as the "transparent vesture" of reason, or love, or whatever other power in the world is regarded as highest.

I have now arrived at the conclusion that was sought. I have tried to show, not only that the attempt to interpret nature in terms of man is not a superstitious anthropomorphism, but that such an interpretation is implied in all rational thought. In other words, self-consciousness is the key to all the problems of nature. Science, in its progress, is gradually substituting one category for the other, and every one of these categories is at once a law of thought and a law of things as known. Each category, successively adopted, lifts nature more to the level of man; and the last category of modern thought, namely, development, constrains us so to modify our views of nature, as to regard it as finally explicable only in the terms of spirit. Thus, the movement of science is towards idealism. Instead of lowering man, it elevates nature into a potency of that which is highest and best in man. It represents the life of man, in the language of philosophy, as the return of the highest to itself; or in the language of our poet, and of religion, as a manifestation of infinite love. The explanation of nature from the principle of love, if it errs, errs "because it is not anthropomorphic enough," not because it is too anthropomorphic; it is not too high and concrete a principle, but too low and abstract.

It now remains to show that the poet, in employing the idea of evolution, was aware of its upward direction. I have already quoted a few passages which indicate that he had detected the false use of it. I shall now quote a few others in which he shows a consciousness of its true meaning: