Let me now turn to the history of humanity as revealed to us in our book. Every monad, or spirit-element, beginning its course by becoming separated from what I conceive as the great central reservoir of Nature, must, before returning thither, make a certain fixed round through an individual existence. If it belongs to the planetary chain, of which our earth is the fourth and lowest link, it must pass seven times through each of the kingdoms of Nature on each one of the seven planets. Of these seven planets, Mars, our Earth, and Mercury, are three. The other four are too tenuous to be cognizable by our present senses. Of the seven kingdoms of Nature, three are likewise beyond our ken or conception; the highest four are the mineral, the vegetable, the animal, and man. Our immortal part has therefore passed already through six of the kingdoms of its destiny, and is, in fact, now near the middle of its fourth round of human existence upon the earth. One life on earth is, however, not sufficient for the development of our powers. Every human being must pass through each of the seven branch races of each of the sub-races of each of the root-races of humanity; and must, in short, live, or, as our author expresses the idea, be incarnated about eight hundred times--some more and some less--upon this planet, before the hour will come when it will be permitted to him, by a path as easy of passage for him then, as is that followed by the rays of light, to visit the planet Mercury, for his next two million years of existence.