370 



NATURE 



[August i8, 1904 



darkness to which they are predestined. Vvhat, then, are 

 we to think of the invisible multitude of the heavenly bodies 

 in which this process has been already completed? Accord- 

 ing to the ordinary view, we should suppose them to be in 

 a state where all possibilities of internal movement were 

 exhausted. At the temperature of interstellar space their 

 constituent elements would be solid and inert ; chemical 

 action and molecular movement would be alike impossible, 

 and their e.\hausted energy could obtain no replenishment 

 unless they were suddenly rejuvenated by some celestial 

 collision, or travelled into other regions warmed by newer 

 suns. 



This view must, however, be profoundly modified if we 

 accept the electric theory of matter. We can then no longer 

 hold that if the internal energy of a sun were as far as 

 possible converted into heat either by its contraction under 

 the stress of gravitation or by chemical reactions between 

 its elements, or by any other inter-atomic force; and that, 

 were the heat so generated to be dissipated, as in time it 

 must be, through infinite space, its whole energy would be 

 exhausted. On the contrary, the amount thus lost would 

 be absolutely insignificant compared with what remained 

 stored up within the separate atoms. The system in its 

 corporate capacity would become bankrupt — the wealth of 

 its individual constituents would be scarcely diminished. 

 They would lie side by side, without movement, without 

 chemical affinity ; yet each one, howsoever inert in its 

 external relations, the theatre of violent motions, and of 

 powerful internal forces. 



Or, put the same thought in another form. When the 

 sudden appearance of some new star in the telescopic field 

 gives notice to the astronomer that he, and perhaps, in the 

 whole universe, he alone, is witnessing the conflagration 

 of a world, the tremendous forces by which this far-off 

 tragedy is being accomplished must surely move his awe. 

 Yet not only would the members of each separate atomic 

 system pursue their relative course unchanged, while the 

 atoms themselves were thus riven violently apart in flaming 

 vapour, but the forces by which such a world is shattered 

 are really negligible compared with those by which each 

 atom of it is held together. 



In common, therefore, with all other living things, we 

 seem to be practically concerned chiefly with the feebler 

 forces of Nature, and with energy in its least powerful 

 manifestations. Chemical aflinity and cohesion are on this 

 theory no more than the slight residual effects of the internal 

 electrical forces which keep the atom in being. Gravita- 

 tion, though it be the shaping force which concentrates 

 nebulas into organised systems of suns and satellites, is 

 trifling compared with the attractions and repulsions with 

 which W'e are familiar between electrically charged bodies ; 

 while these again sink into insignificance beside the attrac- 

 tions and repulsions between the electric monads themselves. 

 The irregular molecular movements which constitute heat, 

 on which the very possibility of organic life seems absolutely 

 to hang, and in whose transformations applied science is at 

 present so largely concerned, cannot rival the kinetic energy 

 stored within the molecules themselves. This prodigious 

 mechanism seems outside the range of our immediate 

 interests. We live, so to speak, merely on its fringe. It 

 has for us no promise of utilitarian value. It will not drive 

 our mills ; we cannot harness it to our trains. Yet not less 

 on that account does it stir the intellectual imagination. 

 The starry heavens have from time immemorial moved the 

 worship or the wonder of mankind. But if the dust beneath 

 our feet be indeed compounded of innumerable systems, 

 whose elements are ever in the most rapid motion, yet 

 retain through uncounted ages their equilibrium unskaken, 

 we can hardly deny that the marvels we directly see are not 

 more worthy of admiration than those which recent dis- 

 coveries have enabled us dimly to surmise. 



Now, whether the main outlines of the world-picture which 

 I have just imperfectly presented to you be destined to 

 survive, or whether in their turn they are to be obliterated 

 by some new drawing on the scientific palimpsest, all will, 

 I think, admit that so bold an attempt to unify physical 

 nature excites feelings of the most acute intellectual gratifi- 

 cation. The satisfaction it gives is almost aesthetic in its 

 intensity and quality. We feel the same sort of pleasurable 

 shock as when from the crest of some melancholy pass we 

 first see far below us the sudden glories of plain, river, and 



NO. 18 I 6, VOL. 70] 



mountain. Whether this vehement sentiment in favour of 

 a simple universe has any theoretical justification I will 

 not venture to pronounce. There is no a priori reason that 

 I know of for expecting that the material world should be 

 a modification of a single medium, rather than a composite 

 structure built out of sixty or seventy elementary substances, 

 eternal and eternally different. Why, then, should we feel 

 content with the first hypothesis and not with the second? 

 Yet so it is. Men of science have always been restive under 

 the multiplication of entities. They have eagerly noted any 

 sign that the chemical atom was composite, and that the 

 different chemical elements had a common origin. Nor, 

 for my part, do I think such instincts should be ignored. 

 John Mill, if I rightly remember, was contemptuous of those 

 who saw any difficulty in accepting the doctrine of " action 

 at a distance." So far as observation and experiment can 

 tell us, bodies do actually influence each other at a distance. 

 And why should they not? Why seek to go behind ex- 

 perience in obedience to some a priori sentiment for which 

 no argument can be adduced? So reasoned Mill, and to 

 his reasoning I have no reply. Nevertheless, we cannot 

 forget that it was to Faraday's obstinate disbelief in " action 

 at a distance " that we owe some of the crucial discoveries 

 on which both our electric industries and the electric theory 

 of matter are ultimately founded ; while at this very moment 

 physicists, however baffled in the quest for an explanation 

 of gravity, refuse altogether to content themselves with the 

 belief, so satisfying to Mill, that it is a simple and in- 

 explicable property of masses acting on each other across 



serve, I think, more attention than has yet been given to 

 them. That they exist is certain ; that they modify the 

 indifferent impartiality of pure empiricism can hardly be 

 denied. The common notion that he who would search out 

 the secrets of Nature must humbly wait on experience, 

 obedient to its slightest hint, is but partly true. This may 

 be his ordinary attitude ; but now and again it happens that 

 observation and experiment are not treated as guides to be 

 meekly followed, but as witnesses to be broken down in 

 cross-examination. Their plain message is disbelieved, and 

 the investigating judge does not pause until a confession 

 in harmony with his preconceived ideas has, if possible, been 

 wrung from their reluctant evidence. 



This proceeding needs neither explanation nor defence in 

 those cases where there is an apparent contradiction between 

 the utterances of e.xperlence in different connections. Such 

 contradictions must of course be reconciled, and science 

 cannot rest until the reconciliation Is effected. The difficulty 

 really arises when e.xperlence apparently says one thing and 

 scientific instinct persists in saying another. Two such cases 

 I have already mentioned ; others will easily be found by 

 those who care to seek. What is the origin of this instinct, 

 and what its value ; whether it be a mere prejudice to be 

 brushed aside, or a clue which no wise man would disdain 

 to follow, I cannot now discuss. For other questions there 

 are, not new, yet raised in an acute form by these most 

 modern views of matter, on which I would ask your in- 

 dulgent attention for yet a few moments. 



That these new views diverge violently from those 

 suggested by ordinary observation is plain enough. No 

 scientific education Is likely to make us, in our unreflective 

 moments, regard the solid earth on which we stand, or 

 the organised bodies with which our terrestrial fate is so 

 intimately bound up, as consisting wholly of electric monads 

 very sparsely scattered through the spaces which these frag- 

 ments of matter are, by a violent metaphor, described as 

 " occupying." Not less plain is it that an almost equal 

 divergence is to be found between these new theories and 

 that modification of the common-sense view of matter with 

 which science has in the main been content to work. 



What was this modification of common sense? It is 

 roughly indicated by an old philosophic distinction drawn 

 between what were called the " primary " and the 

 " secondary " qualities of matter. The primary qualities, 

 such as shape and mass, were supposed to possess an exist- 

 ence quite independent of the observer ; and so far the theory 

 agreed with common sense. The secondary qualities, on 

 the other hand, such as warmth and colour, were thought 

 to have no such independent existence, being, indeed, no 

 more than the resultants due to the action of the primary 



