The determinations which take place in nature occur not at random, but according to a plan--an objective idea. Thus the question is not simply what causes a body to take some direction, but what causes it to take, among the infinite number of possible directions, the proper direction in relation to the idea. In the formation of, say, the leaf of a tree, no two molecules move in identically the same direction or take identically the same path. But each molecule must move in relation to the objective idea of the leaf, or no leaf would be formed. The grand question, therefore, is, What is it that selects from among the infinite number of possible directions the proper one in relation to this idea? And this sort of thing is going on in every blossom and leaf and blade of grass, in every hair and every feather over the surface of the earth. Truly does our author find here "The Grand Question," for in it we touch the very heart of our whole problem, and are forced to consider more closely than we have hitherto done of what character must be the ultimate Cause which alone can explain the world. It is, as we have seen, a first principle of Science, that in enquiries such as this, we must proceed from experience to inference, from the known to the unknown. Arguing thus, we may legitimately gather from observed phenomena, that something exists, which even though it be not directly within the range of our senses, must certainly be capable of producing such phenomena: just as the perturbations of one planet have revealed the existence of another; and the lines in their spectra have taught us the chemical constitution of the sun and stars. This principle being borrowed by Science from common-sense, has instinctively been ever adopted by those who set themselves to enquire of what kind must be that unseen Power at the back of Nature to which the fact of law and order may be ascribed. And as there is but one force or power within the range of our experience capable of producing such an effect, it is but natural that this should have been constantly assumed to represent, at least by analogy, the nature of the power required. That there is but one cause known to us experimentally, which can determine the operation of force towards the attainment of a preconditioned result, none will deny--namely the purposive action of an intelligent will, as known to us in ourselves and in our fellow-men;--and to Will accordingly, immensely more intelligent than ours, has been ascribed the establishment of those laws which the highest intellects of our race are able partially and dimly to apprehend.