There is a law of heredity: like produces like. But why is there such a law? Why does like produce like? Why should not all nature have been sterile? Why should there have been any provision for the propagation of life in a universe ruled by a mere blind force? And why should producer and produced be like? Why should offspring not always be as unlike their parents as tadpoles are unlike frogs? The offspring of all the higher animals pass through various embryological stages in which they are extremely unlike their parents. Why should they ever become like to them? Physical science cannot answer these questions; but that is no reason why they should not both be asked and answered. I can conceive of no other intelligent answer being given to them than that there is a God of wisdom, who designed that the world should be for ages the abode of life; that the life therein should be rich and varied, yet that variation should have its limits; that there should be no disorder or confusion; and who, to secure this result, decreed that plants should yield seeds, and animals bring forth, after their kind. He who would disprove design must certainly not start with the great mystery of generation. Then, the so-called law of variability is the expression of a purpose which must have Reason at its beginning, middle, and end. There is in no organism an absolutely indefinite tendency to vary. Every variation of every organism is in some measure determined by the constitution of the organism. "A whale," as Dr Huxley says, "does not tend to vary in the direction of producing feathers, nor a bird in the direction of producing whalebone." But a tendency to definite variation is an indication of purpose. If a man could make a revolving barrel with a tendency to develop into a watch, he would have to be credited with having designed both the barrel and watch, not less than if he had contrived and constructed the two separately. Further, variation has proceeded in a definite direction. Darwin admits that there is no law of necessary advancement. There is no more reason in the nature of the case for improvement than for deterioration. Apart from the internal constitution of an organism having been so planned, and its external circumstances so arranged, as to favour the one rather than the other, its variations could not have been more towards self-perfection than self-destruction. But variation, according to the Darwinians, has taken place in one direction and not in another; it has been forward, not backward; it has been a progression, not a retrogression. Why? Only because of a continuous adjustment of organisms to circumstances tending to bring this about. Had there been no such adjustment, there might have been only unsuitable variations, or the suitable variations might have been so few and slight that no higher organisms would have been evolved. Natural selection might have had no materials, or altogether insufficient materials, to work with.