A man counting as hard as he can repeat numbers one after another, and never counting more than a hundred, so that he shall have no long words to repeat, may perhaps count ten thousand, or a hundred a hundred times over, in an hour. At this rate, counting night and day, and allowing no time for rest or refreshment, he would count one million in four days and four hours, or say four days only. To count a million a million times over, he would require four million days, or roughly ten thousand years; for five hundred millions of millions, he must have the utterly unrealisable period of five million years. Yet he actually goes through this stupendous piece of reckoning unconsciously hour after hour, day after day, it may be for eighty years, _often in each second_ of daylight; and how much more by artificial or subdued light I do not know. He knows whether his eye is being struck five hundred millions of millions of times, or only four hundred and eighty-two millions of millions of times. He thus shows that he estimates or counts each set of vibrations, and registers them according to his results. If a man writes upon the back of a British Museum blotting-pad of the common _nonpareil_ pattern, on which there are some thousands of small spaces each differing in colour from that which is immediately next to it, his eye will, nevertheless, without an effort assign its true colour to each one of these spaces. This implies that he is all the time counting and taking tally of the difference in the numbers of the vibrations from each one of the small spaces in question. Yet the mind that is capable of such stupendous computations as these so long as it knows nothing about them, makes no little fuss about the conscious adding together of such almost inconceivably minute numbers as, we will say, 2730169 and 5790135—or, if these be considered too large, as 27 and 19. Let the reader remember that he cannot by any effort bring before his mind the units, not in ones, _but in millions of millions_ of the processes which his visual organs are undergoing second after second from dawn till dark, and then let him demur if he will to the possibility of the existence in a germ, of currents and undercurrents, and rhythms and counter rhythms, also by the million of millions—each one of which, on being overtaken by the rhythm from without that chimes in with and stimulates it, may be the beginning of that unsettlement of equilibrium which results in the crash of action, unless it is timely counteracted.