antecedents into consequents of some previous fact; to show that one or more of the causative elements are the same that are productive of other effects; and, lastly, to reproduce the effect by supplying the causative conditions, or to prove the nature of the constant antecedent by experiment. As to the essence of causation or of force, in any of its aspects, we are no wiser than Newton, the profoundest student of its laws, and the readiest to confess his ignorance of its intimate nature. Let us look first at the theological relations of an inquiry into the causes and nature of life. These, if nothing else, may, we think, be satisfactorily adjusted. Every action, or series of actions, is referred by the mind to a force, and this again to a power. Thus the action of a clock is referred to the force of the spring, and this force is the manifestation of a power stored in the spring by winding it up, and set free by giving the first swing to the pendulum. We may consider action as the specific application of force; force, as the transfer of power, or power in transitu; power itself, as the original or delegated source of being, or of change in its condition. Thus life, which appears as a series of actions, is referred to a force commonly called vital, and this to a power, having its centre in the Divine Being; for all who recognize a Divinity are agreed that all power comes from him. This is what they mean when they call omnipotence one of his attributes. The first manifestations of force are habitually referred to the same original source. Thus we say that the Creator gave motion to the planets in it for granted that the Master-hand alone could impart their original impulse. If, however, we are asked why they continue to roll on, we are told that the vis inertiæ keeps them from stopping. But this is a mere name, and we might as well say that the vis motus starts a planet, as that the vis inertiæ keeps it going. A simpler statement is that the Divine agency, once in operation, never changes without cause. We cannot allow force to be self-sustaining any more than self-originating, nor matter itself to be self-subsistent any more than self-creating. "Actualia dependent a Deo tum in existendo, tum in agendo." "Neque male docetur conserva space, taking tionem divinam esse continuatam creationem, ut radius continue a sole prodit." Such are the words of Leibnitz. The apparent uniformity of force, and the seeming independent existence of matter, lead us to speak of them as if their laws, as we term them, were absolutely and eternally inherent. But a law which an omnipotent, omniscient, omnipresent Being enforces, is plainly nothing more than the Lawgiver himself at work. This is the meaning of that somewhat startling utterance of Oken, "The universe is God rotating." Transcendental Physiology is beginning to steal from the hymnbooks. "With glory clad, with strength arrayed, So sang Tate and Brady, paraphrasing the royal David. And Watts, still more expressly, in the hymn made famous by "the harp of thousand strings": — "His Spirit moves our heaving lungs, Or they would breathe no more." Once giving in our complete adhesion to the doctrine of the "immanent Deity," we get rid of many difficulties in the way of speculative inquiry into the nature and origin of things. This may be an important preliminary. Mr. Newport, the very distinguished physiological anatomist, communicated a paper to the Linnæan Society, in the year 1845, "On the Natural History of the Oil Beetle, Meloë." It contained the following sentence: "The facts I have now detailed lead me, in conformity with the discovery by Faraday of the analogy of light with heat, magnetism, and electricity, to regard light as the primary source of all vital and instinctive power, the degrees and variations of which may, perhaps, be referred to modifications of this influence on the special organization of each animal body." The Council of the Society objected to the publication of the passage from which this is extracted. The Society's Index Expurgatorius would have been more complete, if it had included the Invocation of the third book of Paradise Lost, which has hitherto escaped the Anglican censorship. But if the student of nature and the student of divinity can once agree that all the forces of the universe, as well as all its power, are immediately dependent upon its Creator, that He is not only omnipotent, but omnimovent, we have no longer any fear of nebular theories, or doctrines of equivocal generation, or of progressive development. If we saw a new planet actually formed in the field of the telescope, or the imaginary "Acarus Crossii" put together "de toutes pièces" under the microscope, true to its alleged pedigree, out of Silex, by Galvanism, it would no more turn us into atheists, than a sight of the mint would make us doubt the national credit. We are ready, therefore, to examine the mystery of life with the same freedom that we should carry into the examination of any other problem; for it is only a question of what mechanism is employed in its evolution and sustenance. We begin, then, by examining the general rules which the Creator seems to have prescribed to his own operations. We ask, in the first place, whether he is wont, so far as we know, to employ a great multitude of materials, patterns, and forces, or whether he has seen fit to accomplish many different ends by the employment of a few of these only. In all our studies of external nature, the tendency of increasing knowledge has uniformly been to show that the rules of creation are simplicity of material, economy of inventive effort, and thrift in the expenditure of force. All the endless forms in which matter presents itself to us are resolved by chemistry into some threescore supposed simple substances, some of these, perhaps, being only modifications of the same element. The shapes of beasts and birds, of reptiles and fishes, vary in every conceivable degree; yet a single vertebra is the pattern and representation of the frame-work of them all, from eels to elephants. The identity reaches still further, -across a mighty gulf of being, but bridges it over with a line of logic as straight as a sunbeam, and as indestructible as the scymitar-edge that spanned the chasm in the fable of the Indian Hades. Strange as it may sound, the tail which the serpent trails after him in the dust, and the head of Plato, were struck in the die of the same primitive conception, and differ only in their special adaptation to particular ends. Again, the study of the movements of the universe has led us from their complex phenomena to the few simple forces from which they flow. The falling apple and the rolling planet are shown to obey the same tendency. The stick of sealing-wax that draws a feather to it, is animated by the same impulse that convulses the stormy heavens. These generalizations have simplified our view of the grandest material operations, yet we do not feel that creative power and wisdom have been shorn of any single ray by the demonstrations of Newton or of Franklin. On the contrary, the larger the collection of seemingly heterogeneous facts we can bring under the rule of a single formula, the nearer we feel that we have reached towards the source of knowledge, and the more perfectly we trace that little arc of the immeasurable circle which comes within the range of our hasty observations, at first like the broken fragments of a many-sided polygon, but at last as a simple curve that encloses all we know or can know of Nature. To our own intellectual wealth, the gain is like that of the over-burdened traveller, who should exchange hundred-weights of iron for ounces of gold. Evanescent, formless, unstable, impalpable, a fog of uncondensed experiences hovers over our consciousness like an atmosphere of uncombined gases. One spark of genius shoots through it, and its elements rush together and glitter before us in a single translucent drop. It would hardly be extravagant to call Science the art of packing knowledge. We are moving in the right direction, therefore, when we summon all the agencies of nature before the tribunal of Science, and try the question of their identity under their various aliases, just so often as a new set of masks or disguises is detected in their possession. The accumulated discoveries of late years have resulted in such a trial. Following the same course that Newton and Franklin followed in their generalizations, living philosophers have attempted to show relations of mutual convertibility, if not of identity, between the series of forces known as light, heat, electricity, magnetism, and chemical affinity. Some leading facts indicating their intimate relationship may be very briefly recalled. A body heated to a certain point becomes luminous; its heat seems to pass over partly into the condition of light. Thus iron becomes red-hot at about 1,000° Fahrenheit. Light may, perhaps, be changed into, or manifest itself as heat. In Franklin's famous experiment, the black cloth, which absorbs all the luminous rays, sinks deepest into the snow. Light, again, may act chemically, as heat does, as we see in the results of photography. It may be fixed in a body, like heat, as is shown in the Bologna phosphorus, which shines for some minutes after being exposed to sunlight, or to the common light of day. Heat develops electricity, as in the various thermo-electric combinations of different metals. Electricity produces light, and sets fire to combustibles. The highest magnetic powers are developed in iron by the action of galvanic electricity. The magnet, again, is made to give galvanic shocks in a common form of battery, with the usual manifestations of light and heat. Chemical force develops light, heat, and electricity; and each of these is used constantly in the laboratory as a practical means of inducing chemical action. Heat alone is shown, by an experiment of Mr. Grove, to be capable of decomposing water. Further than this, as all forms of motion are capable of developing heat, or light, or electricity, according to the conditions under which it occurs, and as heat and electricity and chemical changes are habitually used to produce motion, it is questioned whether all the apparent varieties of force are not mutually convertible, there being in reality but one kind of force, which manifests itself in each of the different modes just spoken of according to the material substratum through which it is passing, or some other modifying cause. And as there are facts indicating the existence of a system of equivalents as prevailing in these conversions, or of a fixed ratio between the various convertible forms of force, so that a given electrical force will produce just so much heat or chemical decomposition, and either of these reproduce the original amount of electricity, it has been maintained that the total force of the inorganic universe is undergoing perpetual transfer, but never changes in amount, any more than the matter of the universe is altered in quantity by change of form. VOL. LXXXV. — NO. 176. 5 |