CONSTITUENTS OF MATTER 141 



tion of time. The one all-embracing time, like the one 

 all-embracing space, is a construction ; there is no direct 

 time-relation between particulars belonging to my per- 

 spective and particulars belonging to another man's. On 

 the other hand, any two particulars of which I am aware 

 are either simultaneous or successive, and their simul- 

 taneity or successiveness is sometimes itself a datum to 

 me. We may therefore define the perspective to which a 

 given particular belongs as " all particulars simultaneous 

 with the given particular/' where " simultaneous " is to 

 be understood as a direct simple relation, not the deriva- 

 tive constructed relation of physics. It may be observed 

 that the introduction of " local time " suggested by the 

 principle of relativity has effected, for purely scientific 

 reasons, much the same multiplication of times as we 

 have just been advocating. 



The sum-total of all the particulars that are (directly) 

 either simultaneous with or before or after a given par- 

 ticular may be defined as the " biography " to which that 

 particular belongs. It will be observed that, just as a 

 perspective need not be actually perceived by any one, 

 so a biography need not be actually lived by any one. 

 Those biographies that are lived by no one are called 

 " official." 



The definition of a " thing ' is effected by means of 

 continuity and of correlations which have a certain 

 differential independence of other " things." That is to 

 say, given a particular in one perspective, there will 

 usually in a neighbouring perspective be a very similar 

 particular, differing from the given particular, to the first 

 order of small quantities, according to a law involving 

 only the difference of position of the two perspectives in 

 perspective space, and not any of the other " things " in 

 the universe. ' It is this continuity and differential in- 

 dependence in the law ef change as we pass from one 



