Stoney — Natural Science and Ontology. 499 



i. e. if the channel of communication between the sense-compelling 

 auto and me is reopened. 



It thus appears that the phenomenal object is not at all made 

 up of any of the parts of which the sense-compelling auto consists, 

 but only of certain very minute outlying portions of the wide- 

 spread effects of its great activity, viz. those effects which, by its 

 activity, it can produce within me, through a few very narrow 

 and tortuous passages, at the same time that most of its activity is 

 being expended in other directions. This clearly shows (1°) that 

 the phenomenal object is not the auto, and (2°) that for all human 

 purposes my attaining a knowledge of this hypothetical existence 

 is as useful to me as if I knew what the auto is. It tells me, in a 

 direct and in the most compendious form, what effects the auto, under 

 every variety of circumstances, will produce within me, for it is 

 itself a structure built up of these very effeets put together. 



It is to be observed that ordinary language is throughout built 

 upon the popular belief that the objects of the phenomenal world 

 are non-egoistic existences, and moreover that they are the cause of 

 the perceptions which come into existence when we exercise our 

 senses. This is "to put the car before the horse": it is to imagine 

 that a structure built up out of the effects of a thing can be the 

 cause of those effects. The phenomenal object is built up of per- 

 ceptions instead of being the cause of them. Their cause is to be 

 sought in the sense-compelling universe of auta, not in the pheno- 

 menal world of objects. Ordinary language is accordingly apt 

 to mislead us very much ; and we must be constantly on our guard 

 against illusions into which we may but too easily be led by the 

 common usages of language, and by associations which have 

 grown up round familiar forms of expression. 



Illusions will be found to lurk in what are apparently the 

 most harmless forms of expression, such as "I perceive a cloud 

 moving across the sky " — and to get at what we are really jus- 

 tified in believing, it is well diligently to practise ourselves in 

 converting such expressions into less misleading equivalent forms 

 until ive do so with faciliti/. Thus the foregoing statement is 

 equivalent to — 



1°. I am a fluctuating group of associated thoughts, and 

 the perception of a moving cloud is for a short time one of 

 this group. 



