Now to both Science and Christianity, and especially to Science, this enrichment of Evolution is important. And, on the part of Christianity, the contribution to the system of Nature of a second barrier is of real scientific value. At first it may seem merely to increase the difficulty. But in reality it abolishes it. However paradoxical it seems, it is nevertheless the case that two barriers are more easy to understand than one--two mysteries are less mysterious than a single mystery. For it requires two to constitute a harmony. One by itself is a Catastrophe. But, just as the recurrence of an eclipse at different periods makes an eclipse no breach of Continuity; just as the fact that the astronomical conditions necessary to cause a Glacial Period will in the remote future again be fulfilled constitutes the Great Ice Age a normal phenomenon; so the recurrence of two periods associated with special phenomena of Life, the second higher, and by the law necessarily higher, is no violation of the principle of Evolution. Thus even in the matter of adding a second to the one barrier of Nature, the Third Kingdom may already claim to complement the Science of the Second. The overthrow of Spontaneous Generation has left a break in Continuity which continues to put Science to confusion. Alone, it is as abnormal and perplexing to the intellect as the first eclipse. But if the Spiritual Kingdom can supply Science with a companion-phenomenon, the most exceptional thing in the scientific sphere falls within the domain of Law. This, however, is no more than might be expected from a Third Kingdom. True to its place as the highest of the Kingdoms, it ought to embrace all that lies beneath and give to the First and Second their final explanation. How much more in the under-Kingdoms might be explained or illuminated upon this principle, however tempting might be the inquiry, we cannot turn aside to ask. But the rank of the Third Kingdom in the order of Evolution implies that it holds the key to much that is obscure in the world around--much that, apart from it, must always remain obscure. A single obvious instance will serve to illustrate the fertility of the method. What has this Kingdom to contribute to Science with regard to the Problem of the origin of Life itself? Taking this as an isolated phenomenon, neither the Second Kingdom, nor the Third apart from revelation, has anything to pronounce. But when we observe the companion-phenomenon in the higher Kingdom, the question is simplified. It will be disputed by none that the source of Life in the Spiritual World is God. And as the same Law of Biogenesis prevails in both spheres, we may reason from the higher to the lower and affirm it to be at least likely that the origin of life there has been the same.