Stoney — Natural Science and Ontology. 517 



and to other parts of the autic universe. These causal relations 

 change while I am thinking ; and it is to what these causal 

 relations are, and to changes they are undergoing, that we are to 

 attribute the advent into the bystander's mind of the perception of 

 motion. In other words, that perception is the tekmerion sent to 

 him by my thoughts in virtue of their being themselves links in 

 some of the illimitable chains of causes and effects which make up 

 the universe of real existences. 



Turn now to such known facts as that my brain is undergoing 

 wear and tear while I am thinking, and has been replenished by 

 the food I ate yesterday. 



This in the common language of mankind is equivalent to the 

 statement that the oxygen I breathed yesterday, and the vegetables 

 and meat that I ate (or parts of them) are to-day thinking in the 

 same sense in which it can be said that my brain thinks. 



The description which a chemist would give of these events 

 would have an appearance of precision, but would cover but a part 

 of what has happened. He would say — My brain as it existed 

 yesterday consisted of certain chemical atoms variously combined, 

 and going through certain changes of arrangement which are in 

 uninterrupted progress so long as life lasts. Some of these changes 

 are different while I am thinking from what they are when I am 

 not thinking. Part of the change that has taken place since 

 yesterday has consisted in the removal from my brain of many 

 chemical atoms. These have been replaced by other chemical 

 atoms of the same kind, which have been taken in, and which yes- 

 terday were in the food I ate, but to-day are in my brain, and are 

 now combined very nearly in the same way as their predecessors 

 in the brain, and possibly in a different way from the way in 

 which they were combined in the food. 



The account of the same sequence of events which would be 

 given by the student of diacrinomenal nature would be less precise, 

 but at the same time more nearly complete. It would be some- 

 what as follows : — The oxygen, meat, and vegetables I consumed 

 yesterday consisted of motions. Some of these motions have been 

 followed in true dynamical sequence by motions now going on in 

 my brain, which motions in my brain are the events in diacrino- 

 menal nature that are directly associated with some of the thoughts 

 at present in my mind. 



