i6o MYSTICISM AND LOGIC 



described as the space of points of view, since each 

 private world may be regarded as the appearance 

 which the universe presents from a certain point of 

 view. I prefer, however, to speak of it as the space of 

 perspectives, in order to obviate the suggestion that a 

 private world is only real when someone views it. 

 And for the same reason, when I wish to speak of a 

 private world without assuming a percipient, I shall call 

 it a " perspective." 



We have now to explain how the different perspectives 

 are ordered in one space. This is effected by means of the 

 correlated " sensibilia " which are regarded as the appear- 

 ances, in different perspectives, of one and the same thing. 

 By moving, and by testimony, we discover that two 

 different perspectives, though they cannot both contain 

 the same " sensibilia," may nevertheless contain very 

 similar ones ; and the spatial order of a certain group of 

 "sensibilia" in a private space of one perspective is 

 found to be identical with, or very similar to, the spatial 

 order of the correlated " sensibilia " iff the private space 

 of another perspective. In this way one " sensibile " in 

 one perspective is correlated with one "sensibile" in 

 another. Such correlated " sensibilia " will be called 

 *' appearances of one thing." In Leibniz's monadology, 

 since each monad mirrored the whole universe, there was 

 in each perspective a " sensibile " which was an appear- 

 ance of each thing. In our system of perspectives, we 

 make no such assumption of completeness. A given 

 thing will have appearances in some perspectives, but 

 presumably not in certain others. The " thing " being 

 defined as the class of its appearances, if k is the class of 

 perspectives in which a certain thing appears, then 6 is 

 a member of the multiplicative class oi k , k being a class 

 of mutually exclusive classes of " sensibilia." And 



