Stoney — Natural Science and Ontology. 481 



universe, the phenomenal object is fully entitled to be called real, 

 as opposed to illusory or imaginary. (Essay, pp. 502 and 506). 



18. We may liken the sense-compelling part of the universe 

 to a great machine in motion, and the perceptions it produces 

 within the human mind to shadows cast by it. The laws of the 

 movements of the machine are the real laws of the universe ; the 

 laws of Nature are but the laws of the changes which the shadows 

 in consequence undergo. (Essay, p. 502.) 



19. (a) Natural objects \ Have only an objective existence, 



(b) Space relations > not an autic existence. See § 12, 



(c) Motions J above. (Essay, p. 507.) 



They are, however, real in the sense in which that term is used in 

 § 17. (Essay, p. 508.) 



20. The exigencies of scientific inquiry have led to the concep- 

 tion of parts o,f phenomenal objects, and of motions, which are 

 smaller than any that are built up of perceptions that man's senses 

 can convey to him (Essay, p. 509) ; so that the phenomenal object 

 of the scientific man consists of — 



1. Actual perceptions ; 



2. Potential perceptions ; and of 



3. Certain other conceived perceptions. 



21. Furthermore, in substitution for the phenomenal objects of 

 Nature, scientific investigation has led inquirers to conceive space 

 as peopled with objects that consist exclusively of motions. These 

 may be called diacrinomenal objects to distinguish them from 

 the phenomenal objects for which they are substituted ; and the 

 totality of them may be called Diacrinomenal Nature. See Dia- 

 gram I. (Essay, p. 509.) 



22. It is obvious that causation, when that term is understood to 

 include efficiency in the cause, can only prevail among auta. It has 

 no place in the study of phenomenal or of diacrinomenal nature, i.e., 

 in the domain of physical science. (Essay, p. 510.) 



23. The assumption that material " substances" and that forces 

 exist, and that the former occupy positions in space the same as or 

 near to those which the phenomenal objects appear to occupy, is the 

 commonly received noiimenal hypothesis. (By a noiimenal 

 hypothesis is to be understood an hypothesis as to what the auta of 

 the sense-compelling universe are.) (Essay, p. 515.) 



