that every kind of motion at any moment perceptible--whether in the form of movement through space, or of light, or heat, or electricity, or the actinism that builds up the green stuff in the leaves of plants--owes its existence to the metamorphosis of some previous kind of motion. Every living organism is a marvellous aggregate of divers forms of matter performing divers characteristic motions, and the sum total of these motions is the whole of life, as regarded purely on its physical side. When we take food we bring into the system sundry nitrogenous and hydrocarbon compounds, each of which is alive with little energies or latent capacities for certain kinds of motion. The oxygen of the air, especially in its unstable form of ozone, is a powerful inciter of chemical motions, and when we breathe it in, the little latent capacities presently become actual motions. Some of them are realized in the rhythmical movements of heart and lungs, some in the undulations that sustain the animal temperature, some in the formation of the tiny drops that collect in a secreting gland, some in the repair of tissue by the substitution of new complex molecules for old ones that are broken down, some in the contraction of a group of muscles, some in the changes within the substance of nerve that accompany conscious thought, sensation, and volition. Ah, yes, here we come to it at last! We do not doubt that all these myriad motions are members in a series of transformations, wherein the appearance of each results from the disappearance of its predecessors. We have neither the instruments nor the calculus to prove this in the infinite multitude of details, but the general theory has been so completely established wherever it is accessible to instruments and calculus that we can have no hesitation in granting its universality wherever matter and motion are concerned in any shape or amount. No scientific man will for a moment doubt that the little vibratory discharge between cerebral ganglia which accompanies a thought is one member in a series of molecular motions that might be measured and expressed in terms of quantity if we only possessed an apparatus sufficiently delicate and subtle. Now if such is the case with the little physical motion within the brain, how is it with the accompanying thought? Does the correlation obtain between physical motions and conscious feelings? Are states of consciousness links in the Protean series of motions, in such wise that the vibration within the brain produces the thought or feeling? In other words is the thought or feeling merely a transformed vibration? Does a certain amount of vibration perish to be replaced by an exact equivalent in the shape of thought? and then does the thought perish in the act of giving place to other vibrations which end in a visible motion of muscles? as when, for example, you hear the sound of a bell and start toward the door.