If you think this old-world and idle speculation, I need only refer you to Descartes, the father of modern scientific metaphysic, who held that his two universal factors, extension and thought, were after all but qualities of the one all-embracing substance which he called God; or I may refer to Spinoza, the spiritual pupil of Descartes, and the most important Pantheist of the seventeenth, or perhaps of any, century. The positive arguments in favour of this subtle speculation, which to the vulgar public of any age must always remain absurd, were in the first place the untrustworthy character of our senses, which could be shown not only to be misleading but to give contradictory reports concerning the same thing; next the general consent of all thinkers that there must be something permanent and indestructible in the midst of all the changes of phenomena; then the inability of any perceived substance, such as water, or air, however subtle, to satisfy this condition of permanence, and to take a position superior to the attacks of rival theories. You must therefore abstract more and more from all qualities till you reach that pure Being, which is all and none, spirit and body, unity and infinity, eternal, indestructible, invariable, the source and substance of all that ever did or ever will exist. You can well imagine how these splendid dreams were regarded by the clever and practical Greek public, as indeed they have been by average men from that day to this, whenever the great theory has been stated afresh by metaphysicians or by mystics. It was the special merit of the Eleatic Zeno (not the great Stoic who lived far later) to show the carping critic that the difficulties which had led the philosopher to discard the senses as guides to truth, can be raised in the case of the common facts of our everyday life, and that the scoffer cannot solve them. I lay stress on these intellectual puzzles, because they have occupied philosophers perpetually down to the present day, and in no particular case can we affirm more decidedly that the Greeks were the fathers of modern thinking. And do not for a moment imagine that because these subtleties lead to no immediate result, they are therefore barren. You might as well say that physical games and exercises are of no use, because they merely result in strengthening and improving the human frame and the human temper, apart from any further result. Now what were Zeno’s puzzles? I will mention but the most obvious. Is it conceivable that sound should be made up of non-sounding things? And yet this absurdity is demonstrable. Drop a single millet seed from your hand upon the grass. It will not make the smallest noise. Go on with a second, a third, and so on, till you reach thousands; it is so with them all. Yet if you turn out a cartful of such seeds, it will make a considerable noise. How is it possible, if each individual grain is silent? Again,