October 22, 1886.] 



SCIENCE, 



377 



of all phenomena, and attacking his problems 

 from both points of view. To the physicist a 

 body is a piece of matter exhibiting certain proper- 

 ties under certain conditions : to the psychologist 

 it is a complex of sensations. For many purposes 

 it is advisable to keep these tilings separate. But 

 the convenience arising from this separation gave 

 rise to the false notion that the two things had 

 little or nothing in common, and, if useless meta- 

 physical questions were to be avoided, had better 

 have little in common. It was an example of 

 over-specialization. Helmholtz showed, that, 

 apart from any metaphysical notions or discussions, 

 a large common field lay open, where the com- 

 bined forces of physics and psychology could and 

 ought to unite to shed new light on a most im- 

 portant department of scientific research. 



Helmholtz was not long without followers in 

 his rich line of work, and foremost among these 

 is Professor Mach of the University of Prague. 

 He, too, is a physicist, but was constantly driven 

 to a study of the senses by the wide point of view 

 from which he regarded his science. He is best 

 known as a psychologist by his study of the sen- 

 sations accompanying motion. In these he con- 

 trived an ingenious apparatus by which persons 

 were swung around in various directions, and the 

 inference drawn from the nature of the vertigo 

 caused by the revolutions, that the semicircular 

 canals of the internal ear, which experiments on 

 animals had shown to be a mechanism for main- 

 taining equilibrium, served a similar function in 

 man. He has also repeated and added to the 

 analysis of tone sensations which Helmholtz made. 

 His work is characterized throughout by an 

 unusual ingenuity, great accuracy, and a clear and 

 easy exposition. 



In a recent publication ^ he has added some 

 highly suggestive studies in the sphere of sight 

 and hearing, and accompanied them by a state- 

 ment of the point of view from which he regards 

 the study of the senses. It is to the latter that 

 attention is to be briefly called. 



" Through the deep conviction that science in 

 general, and physics in particular, is to expect the 

 next great advancements with regard to its funda- 

 mental position from biology, and more especially 

 from the analysis of sensation, I have been repeat- 

 edly drawn into that field." This the opening 

 sentence of his preface may be regarded as a text. 

 Before proceeding with his argument, he wants to 

 clear the ground by a few ' anti-metaphysical ' 

 remarks. In the first place, as to what a thing is. 

 It is what can be perceived by the mind at once : 

 it is this that gets a name. An apple is a complex 



1 Beitrage zur analyse der empfindunger. Von Dr. E. 

 Mach. Jena, 1886. 



of visible, tangible, smellable, tastable qualities. 

 One's self is a more constant complex of such and 

 other sensations associated with the body. By a 

 comparison of various such complexes of sensa- 

 tions, we analyze them, and divide oflf the visible, 

 tangible, etc. The visible, again, we divide into 

 form and color, and these are our elements. The 

 body is only the sum of the sensations to which it 

 can give rise. The illusion that because we can 

 abstract each of these sensations separately, and 

 still retain the body, we can do so with all at once, 

 has given rise to' the metaphysical ' thing per se.' 

 The chasm between physics and psychology exists 

 only in our stereotyped mode of presentation. A 

 color is a physical object when we consider its 

 dependence on the sovirce of light, its relation to 

 other colors, its heat-giving properties, etc. : it is a 

 psychological object when we consider its depend- 

 ence on the retina. In the first case we trace a 

 relation between two series of phenomena : in the 

 second case one of the series is replaced by a thnd, 

 of different nature. It is the point of view that 

 makes the difference. "We avoid the conflict be- 

 tween the physical and psychological points of 

 view by considering sensations as the ultimate 

 elements. This, too, is not to be regarded as the 

 permanent, but, as for present purposes, the most 

 economical position. 



The sensation, in turn, can be subjected to a 

 fisychological analysis, can be regarded as a 

 physical (physiological) phenomenon, or its de- 

 pendence on iDhysical processes worked out. The 

 latter, whenever possible, is the ideal goal to be 

 reached. Our gTiiding principle is that of a com- 

 plete parallelism between the psychic and the 

 physical. At times, it is true, more light will be 

 gotten from a purely biological (evolutionary) 

 point of view ; but this, again, can be formulated 

 under the general rule. 



The advantages that physics is to gain from such 

 considerations are many. In the first place, a 

 false conception is eradicated. There is no sub- 

 ject and object, no thing and sensation. Only one 

 kind of elements exists, from which subject and 

 object are built up. The ' sensible ' world is the 

 common property of physics and psychology. It 

 is physics as long as we disregard our own body : 

 it is psychology when that is the special object of 

 research. Again, the physicist will no longer be 

 misled by such imposing entities as matter, atoms, 

 etc. He will recognize their purely secondary and 

 symbolical origin. 



An adaptation of our method of thinking to the 

 facts is the end of science. This goes on uncon- 

 sciously in the daily life of every one : it is 

 education. When raised into a conscious and 

 deliberate object, it becomes scientific research. If 



