Now, it is quite true that “ultimate principles,” in the common understanding of the words, always assume the simplicity of geometrical axioms—(as for “self-evidence,” there is no such thing)—but these principles are clearly _not_ “ultimate;” in other terms what we are in the habit of calling principles are no principles, properly speaking—since there can be but one _principle_, the Volition of God. We have no right to assume, then, from what we observe in rules that we choose foolishly to name “principles,” anything at all in respect to the characteristics of a principle proper. The “ultimate principles” of which Dr. Nichol speaks as having geometrical simplicity, may and do have this geometrical turn, as being part and parcel of a vast geometrical system, and thus a system of simplicity itself—in which, nevertheless, the _truly_ ultimate principle is, _as we know_, the consummation of the complex—that is to say, of the unintelligible—for is it not the Spiritual Capacity of God? I quoted Dr. Nichol’s remark, however, not so much to question its philosophy, as by way of calling attention to the fact that, while all men have admitted _some_ principle as existing behind the Law of Gravity, no attempt has been yet made to point out what this principle in particular _is_:—if we except, perhaps, occasional fantastic efforts at referring it to Magnetism, or Mesmerism, or Swedenborgianism, or Transcendentalism, or some other equally delicious _ism_ of the same species, and invariably patronized by one and the same species of people. The great mind of Newton, while boldly grasping the Law itself, shrank from the principle of the Law. The more fluent and comprehensive at least, if not the more patient and profound, sagacity of Laplace, had not the courage to attack it. But hesitation on the part of these two astronomers it is, perhaps, not so very difficult to understand. They, as well as all the first class of mathematicians, were mathematicians _solely_:—their intellect, at least, had a firmly-pronounced mathematico-physical tone. What lay not distinctly within the domain of Physics, or of Mathematics, seemed to them either Non-Entity or Shadow. Nevertheless, we may well wonder that Leibnitz, who was a marked exception to the general rule in these respects, and whose mental temperament was a singular admixture of the mathematical with the physico-metaphysical, did not at once investigate and establish the point at issue. Either Newton or Laplace, seeking a principle and discovering none _physical_, would have rested contentedly in the conclusion that there was absolutely none; but it is almost impossible to fancy, of Leibnitz, that, having exhausted in his search the physical dominions, he would not have stepped at once, boldly and hopefully, amid his old familiar haunts in the kingdom of Metaphysics. Here, indeed, it is clear that he _must_ have adventured in search of the treasure:—that