For primitive man, as for the poet of all times, everything is alive, and every sound is due to a being with feelings similar to our own. The sighing of the breeze, the moan of the wave upon the shore, the babbling of the brook, the roaring of the sea, and the pealing of the thunder are nothing less than sad, joyous, or angry living voices. These impressions were embodied in ancient mythology, the graceful beauty of which does not conceal its inadequacy. Then they passed into philosophy and approached the realm of science. Thales believed that all bodies in nature were animate and living. Origen considered the stars as actual beings. Even Kepler himself attributed to the celestial bodies an internal principle of action, which, it may be said in passing, is contrary to the law of the inertia of matter, which has been wrongly ascribed to him instead of to Galileo. The terrestrial globe was, according to him, a huge animal, sensitive to astral influences, frightened at the approach of the other planets, and manifesting its terror by tempests, hurricanes, and earthquakes. The wonderful flux and reflux of the ocean was its breathing. The earth had its blood, its perspiration, its excretions; it also had its foods, among which was the sea water which it absorbs by numerous channels. It is only fair to add that at the end of his life Kepler retracted these vague dreams, ascribing them to the influence of J. C. Scaliger. He explained that by the soul of the celestial bodies he meant nothing more than their motive force. § 2. OPINION OF THE PHILOSOPHERS. _Transition from Brute to Living Bodies._—The lowering of the barrier between brute bodies and living bodies began with those philosophers who introduced into the world the great principles of continuity and evolution. _The Principle of Continuity._—First and foremost we must mention Leibniz. According to the teaching of that illustrious philosopher, as interpreted by M. Fouillée, “there is no inorganic kingdom, only a great organic kingdom, of which mineral, vegetable, and animal forms are the various developments.... Continuity exists everywhere throughout the world; everywhere is life and organization. Nothing is dead; life is universal.” It follows that there is no interruption or break in the succession of natural phenomena; that everything is gradually developed; and finally, that the origin of the organic being must be sought in the inorganic. Life, properly so called, has not, in fact, always existed on the surface of the globe. It appeared at a certain geological epoch, in a purely inorganic medium, by reason of favourable conditions. The doctrine of continuity compels us, however, to admit that it pre-existed on the globe under some rudimentary form.