ELEMENTARY PARTICLE — SCHRODINGER 189 



sional formulation the cases iV=0, 1, 2, 3 . . . (to infinity) of the 

 many-dimensional treatment. This highly ingenious device includes 

 the so-called new statistics, with which we shall have to deal below in 

 much simpler terms. It is the only precise formulation of the views 

 now held, and the one that is always used. What is so very significant 

 in our present context is that one cannot avoid leaving indeterminate 

 the number of the particles dealt with. It is thus obvious that they 

 are not individuals. 



7. THE NOTION OF A PIECE OF MATTER 



I wish to set forth a view on matter and the material universe, to 

 which Ernst Mach [1],^ Bertrand Russell [2], and others were led by 

 a careful analysis of concepts. It differs from the popular view. We 

 are, however, not concerned with the psychological origin of the con- 

 cept of matter but with its epistemological analysis. The attitude is 

 so simple that it can hardly claim complete novelty; some pre- 

 Socratics, including the materialist Democritus [3], were nearer to 

 it than were the great men who resuscitated science and molded it 

 during the seventeenth to nineteenth centuries. 



According to this view, a piece of matter is the name we give to a 

 continuous string of events that succeed each other in time, immedi- 

 ately successive ones being as a rule closely similar. The single event 

 is an inextricable complex of sensates, of associated memory images, 

 and of expectations associated with the former two. The sensates 

 prevail in the case of an unknown object, say a distant white patch on 

 the road, which might be a stone, snow, salt, a cat or a dog, a white 

 shirt or blouse, a handkerchief. Even so, within the ensuing string 

 of events we usually know from general experience how to discount 

 the changes caused by motions of our own body, in particular of our 

 direction of sight. As soon as the nature of the object is recognized, 

 images and expectations begin to prevail. The latter concern sensa- 

 tions as hard, soft, heavy, flexible, rough, smooth, cold, salty, etc., 

 associated with the image of touching and handling ; they also concern 

 spontaneous movements or noises such as barking, mewing, shouting, 

 etc. It should be noted that I am not speaking of our thoughts or con- 

 siderations about the object, but of what forms part and parcel of 

 our perception of it — of what it is to us. However, the limit is not 

 sharp. As our familiarity with a piece of matter grows, and in par- 

 ticular as we approach its scientific aspect, the range of expectations 

 in regard to it widens, eventually to include all the information science 

 has ascertained, e. g., melting point, solubility, electric conductivity, 

 density, chemical and crystalline structure, and so on. At the same 

 time, the momentary sensational core recedes in relevance the more 



* Numbers ia brackets refer to authorities cited at the end of this article. 



