174 SENSATION, IDEATION, 



order in which our Sensations and Ideas occur, and the 

 modes in which they combine with one another. 



With respect to the order of our Sensations, it is obvious 

 enough that, to a considerable extent, they occur accord- 

 ing to the order established among what we call the 

 objects and phenomena of nature ; and that these are 

 divisible into two categories : (1) the synchronous order, 

 and (2) the successive order. As James Mill says : "The 

 synchronous order, or order of simultaneous existence, is 

 the order in space ; the successive order, or order of 

 antecedent and consequent existence, is the order in time. 

 Thus the various objects in my room, the chairs, the 

 tables, the books, have the synchronous order, or order in 

 space. The falling of the spark and the explosion of 

 gunpowder have the successive order, or order in time." 



We habitually receive, therefore, synchronous Sensations 

 from external objects co-existing in space, and we as 

 habitually receive trains of successive Sensations follow- 

 ing one another in time. And as Ideas are merely weak 

 copies or revivals of Sensations, it is only, natural to 

 expect that they would, as they do, derive their order in 

 the main from that of our sensations. On this head 

 Herbert Spencer* remarks, " the persistence of the con- 

 nection between states of consciousness is proportionate 

 to the persistence of the connection between the agencies 

 to which they answer. The relations between external 

 objects, attributes, acts, are of all grades from the 

 necessary to the fortuitous. The relations between the 

 answering states of consciousness must similarly be of 

 all grades from the necessary to the fortuitous." 



Now it so happens that " of the objects from which we 

 derive the greatest part of our sensations, most of those 

 which are observed synchronically are frequently observed 



* " Principles of Psychology," vol. i. p. 448. 



