Life does not appear in a hard, immobile, utterly inert world, but in a world thrilling with energy and activity, a world of ceaseless transformations of energy, of radio-activity, of electro-magnetic currents, of perpetual motion in its ultimate particles, a world whose heavens are at times hung with rainbows, curtained with tremulous shifting auroras, and veined and illumined with forked lightnings, a world of rolling rivers and heaving seas, activity, physical and chemical, everywhere.  On such a world life appeared, bringing no new element or force, but setting up a new activity in matter, an activity that tends to check and control the natural tendency to the dissipation and degradation of energy.  The question is, Did it arise through some transformation of the existing energy, or out of the preexisting conditions, or was it supplementary to them, an addition from some unknown source?  Was it a miraculous or a natural event?  We shall answer according to our temperaments.

One sees with his mind’s eye this stream of energy, which we name the material universe, flowing down the endless cycles of time; at a certain point in its course, a change comes over its surface; what we call life appears, and assumes many forms; at a point farther along in its course, life disappears, and the eternal river flows on regardless, till, at some other point, the same changes take place again.  Life is inseparable from this river of energy, but it is not coextensive with it, either in time or in space.

In midsummer what river-men call “the blossoming of the water” takes place in the Hudson River; the water is full of minute vegetable organisms; they are seasonal and temporary; they are born of the midsummer heats.  By and by the water is clear again.  Life in the universe seems as seasonal and fugitive as this blossoming of the water.  More and more does science hold us to the view of the unity of nature—­that the universe of life and matter and force is all natural or all supernatural, it matters little which you call it, but it is not both.  One need not go away from his own doorstep to find mysteries enough to last him a lifetime, but he will find them in his own body, in the ground upon which he stands, not less than in his mind, and in the invisible forces that play around him.  We may marvel how the delicate color and perfume of the flower could come by way of the root and stalk of the plant, or how the crude mussel could give birth to the rainbow-tinted pearl, or how the precious metals and stones arise from the flux of the baser elements, or how the ugly worm wakes up and finds itself a winged creature of the air; yet we do not invoke the supernatural to account for these things.