We shall pass over the period of Evolution in which Matter was evolving into finer and still finer forms, until at last it reached a degree of vibration capable of supporting that which we call "life." Of course there is "life" in all matter--even in the atom, as we have shown in previous lessons. But when we speak of "life," as we now do, we mean what are generally called "living forms." The Yogi Teachings inform us that the lowest forms of what we call "life" were evolved from forms of high crystal life, which indeed they very much resemble. We have spoken of this resemblance, in the previous lessons of this series. And, so we shall begin at the point where "living forms" began. Speaking now of our own planet, the Earth, we find matter emerging from the molten state in which it manifested for ages. Gradually cooling and stratifying, the Earth contained none of those forms that we call living forms. The temperature of the Earth in that period is estimated at about 15,000 times hotter than boiling water, which would, of course, render impossible the existence of any of the present known forms of life. But the Yogi Teachings inform us that even in the molten mass there were elementary forms that were to become the ancestral forms of the later living forms. These elementary forms were composed of a vaporous, peculiar form of matter, of minute size,--little more than the atoms, in fact, and yet, just a little more advanced. From these elementary forms, there gradually evolved, as the Earth cooled and solidified, other forms, and so on until at last the first "living form" manifested. As the globe cooled at the poles, there was gradually created a tropical climate, in which the temperature was sufficiently cool to support certain rudimentary forms of life. In the rocks in the far northern latitudes, there are found abundant traces of fossils, which goes to prove the correctness of the Yogi Teachings of the origin of life at the north pole, from which the living forms gradually spread south toward the equator, as the Earth's surface cooled. The elementary evolving life forms were of a very simple structure, and were but a degree above the crystals. They were composed of identically the same substance as the crystals, _the only difference being that they displayed a greater degree of mind_. For that matter, even the highest physical form known to us today is composed of simple chemical materials. And these chemical materials are obtained, either directly or indirectly, from the air, water, or earth. The principal materials composing the physical bodies of plants, animals, and man, are oxygen, carbon, hydrogen, nitrogen, with a still smaller proportion of sulphur and phosphorus, and traces of a few other elements. The material part of all living things is alike--the difference lies in the degree of Mind controlling the matter in which it is embodied.