the universe that it is possible for it to gather them up in a single series, or, in other words, organize them into one harmonious and logical whole.

It is not difficult to see that the group of relations which yields the mechanical conception radiates from an entirely different centre from that which gives us the conception of the power of the human spirit to modify the mechanical order. The former regards things in their relation to an abstract principle which we call force. The latter regards things in their relation to an abstract principle which we call spirit. They cannot agree with each other, they cannot contradict each other. One cannot be the proof of the other, but no more can it be its disproof. They are on different planes; and how many or how deep may be the strata of reality lying between these two we cannot guess. The unmistakable and all-important fact is that they coexist in experience. And the circumstance that they cannot be brought into one, that we cannot understand how they are complementary, that they even appear to be contradictory, is not a matter for wonder to us. It is just what we ought to expect.

It is what we ought to expect in view of that conception, accepted equally by theology and science, that the universe is an organic whole, dependent upon a central controlling principle or being. If it is assumed that, as viewed from this central position, the cosmos presents the appearance of absolute order and perfect harmony, it follows, necessarily, that when viewed from an extremely one-sided position, treated as the centre, a position like that occupied by the latest product of evolution, man, the appearance of things must be the reverse of harmonious.

But, it may be objected, this proves, or rather assumes, too much. If we are so far removed, by reason of our position, from the possibility of grasping the harmony of the universe, how is it that we have been able to reduce so large a number of its elements to harmony? Instead of finding two great divisions of thought opposed to each other, we ought to detect innumerable discrepancies and impossibilities. This certainly seems a reasonable consideration, but it does not weaken our position. Our answer to it is, that what we ought to find is just what we do find. Our experience, and even our science, is full of just such contrarieties as that which makes mental causation appear to be the antithesis of physical causation; and our basis for reality is not, in truth, twofold, but manifold.

In any comprehensive structure of thought which we build for

ourselves, we have to arch over not one space, but many spaces, whose depth we cannot fathom. How can motion be transferred from one body to another? How can any one atom of matter act upon any other? These questions are equally unanswerable with that which asks how mind can act upon matter. When we ignore these questions, taking the facts which they challenge for granted, this is not because everybody understands all about them, or because they are too simple to require an explanation, — but because physical science cannot touch them; they are not in its plane of operations. And if it seems to us that science has made the problem any more intelligible by such a phrase as the homogeneity of matter," we are simply deceiving ourselves with words. We mistake a mere statement for an explanation.

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As Lotze remarks: "Though it needs but little study of physical science to teach us that all forms of action and reaction between substance and substance are equally obscure, it has yet become a habit, hardly to be overcome, to look upon the mutual influence of body and soul as a particular and exceptional case, in which unfortunately, and contrary to our expectations, that will not become clear which in every example of merely physical action is perfectly intelligible." 1

But what shall we say of those great generalizations of science that disclose the universality of certain principles? Does not the verification of a law like that of the attraction of gravitation, or that of the persistence of force, prove that we are capable of reaching the ultimate truth of the relations of things? Does not every such law of universal application bring us nearer to the goal of a perfectly harmonized conception of the cosmos? On the contrary, the addition of each generalization increases the number of connected views of the universe that hold together when considered each by itself; but which, as related to one another, refuse to be reconciled.

As we have already seen, each one of these is a series of abstractions that regards only certain peculiar characteristics in the objects with which it deals. The farther we push any series of abstractions, therefore, the more isolated is the result reached, isolated both as regards all forms of concrete reality, and also as regards other extreme generalizations. The series of relations which it reduces to a law may be coextensive with the universe; but the very fact that it is the outcome of the last results of abstraction shuts this particular series up to itself.

1 Microcosmus, vol. i. p. 278.

This may seem to the reader to be a harmless assault of purely metaphysical reasoning upon the firmly-compacted, deeply-laid foundations of physical science. We have heard so much about the exactness of modern science, about its carefulness to criticise and prove every step, and we have been told so many times that it is a perfectly consistent and harmonious whole, that an attempt to prove by abstract reasoning that it ought to be disjointed and self-contradictory may seem worthy of a smile rather than serious attention. But here, as once before, our answer is that just what ought to be, for the justification of our reasoning, is. Modern science is not a consistent whole. It is self-contradictory at its foundations. Each series of abstractions which gives rise to what we call a law of nature, though it may be a wonder of precision in itself, is hopelessly in conflict with other generalizations of science that seem to be equally well-grounded.

This has been set forth with startling clearness in the volume 1 from which I have already quoted; and though it is impossible, in short compass, to produce the impression that results from a careful study of it, I will, for the sake of illustration, try to set before the reader some of the conflicts of thought which it exposes to view.

Fundamental to the mechanical theory of the universe is the assumption that the ultimate atoms of mass are equal and perfectly homogeneous. This is a corollary from the proposition that all the diversities in nature are caused by motion. But over against this most essential part of the mechanical theory we have to place a fundamental law of chemistry, the so-called law of Avogadro, or Ampère, which, we are told by Professor Cooke, "now holds the same place in chemistry that the law of gravitation does in astronomy." It is as follows: Equal volumes of all substances, when in the state of gas, and under like conditions, contain the same number of molecules.2

It follows from this that the weights of the molecules must be in proportion to the specific gravities of the gases. But the specific gravities of the gases are different. Having, therefore, different weights to apportion among the same number of molecules in different gases, we are forced to the conclusion that the molecules of one gas weigh more than those of another. As thus stated, it might appear that this difference is true only of compound chemical molecules. But as some substances are monatomic, and

1 Concepts of Modern Science, by J. B. Stallo.

2 The New Chemistry, by Professor J. P. Cooke, p. 13. 1888.

some others have molecules consisting of the same number of atoms, it follows that the ultimate atoms themselves are of different weights. Here, then, we have a contradiction surely not less startling than that which makes the doctrine of the persistence of force the contradiction of the belief in mental causation. But this does not stand alone.

A second fundamental assumption of the mechanical theory is that the elementary units of mass are absolutely hard and inelastic. This is at the same time a necessary postulate of the atomo-mechanical theory, and a necessary antithesis of the doctrine of the conservation of energy or persistence of force. Elasticity cannot be a characteristic of simple atoms, because all elasticity involves motion of parts. The concept elastic atom is, Professor Witwer affirms, "a contradiction in terms." But, on the other hand, Sir William Thomson says we are forbidden, by the modern theory of the conservation of energy, to assume inelasticity, or anything short of perfect elasticity, of the ultimate molecules, whether of ultra-mundane or mundane matter."

The necessity here referred to is imposed upon science by what is known as the kinetic theory of gases. In the light of this theory a gaseous body is a swarm of innumerable solid particles incessantly moving about with different velocities in rectilinear paths of all conceivable directions, the velocities and directions being changed by mutual encounters at intervals, which are short in comparison with ordinary standards of duration, but indefinitely long as compared with the duration of the encounters. Now, if these particles were wholly inelastic, or imperfectly elastic, the motion must soon come to an end.

Stallo draws attention to the fact that distinguished advocates of the kinetic hypothesis have taxed their ingenuity in the search of methods for the extrication of the mechanical theory from the dilemma in which it is thus involved. But, after passing in review the most notable efforts made in this direction, he reaches the following conclusion: "The difficulty, then, appears to be inherent and insoluble. There is no method known to physical science which enables it to renounce the assumption of the perfect elasticity of the particles whereof ponderable bodies and their hypothetical imponderable envelopes are said to be composed, however clearly this assumption conflicts with one of the essential requirements of the mechanical theory." 1

Again, according to the mechanical theory, motion, like mass,

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is indestructible and unchangeable; it cannot vanish and reappear. There is, therefore, no such thing as potential energy. All energy is, in reality, kinetic. But, as in the former case, "modern science peremptorily refuses its assent. It asserts that all, or nearly all, physical changes in the universe are mutual conversions of kinetic and potential energies; that energy is incessantly stored as virtual power and restored as actual motion." To make this clear, our author briefly reviews the history of the doctrine of the persistence of force, and shows that it has been, in effect, a progressive abandonment of the proposition that all potential energy is, in reality, kinetic.

These examples are, perhaps, enough to illustrate our point. But I will adduce one other, which may prove the most impressive of all, because of our familiarity with the law involved. There can hardly be any question as to the preeminence, among scientific discoveries, of that one of Sir Isaac Newton generally called the law of the attraction of gravitation. In one view this law may be said to be the central principle of modern science. Chemistry, as a science of weights, is built upon it as really as astronomy and physics. What, then, shall we make of the fact that it is, in another aspect, the absolute contradiction of the fundamental postulates of scientific thought? that it refuses all classification with other known physical forces as absolutely as the concept spirit?

A postulate of the mechanical theory universally accepted by physicists has been that all physical action is by impact. The elementary units of mass are absolutely inert, therefore a mass can have motion induced in it only by contact with another mass. In short, there are in nature no pulls but only thrusts. All force is not merely vis impressa, but vis a tergo. There cannot be any such thing, therefore, as action at a distance. The reason for this is set forth substantially as follows by Professor Challis. There is no other kind of force than pressure by contact of one body with another. This hypothesis is made on the principle of admitting no fundamental ideas that are not referable to sensation and experience. It is true that we see bodies obeying the influence of an external force, as when a body descends toward the earth by the action of gravity; so far as the sense of sight informs us we do not in such cases perceive either the contact or the presence of another body. But we have also the sense of touch or of pressure by contact, for instance, of the hand with another body; and we feel in ourselves the power of causing motion by such pressure.