512 THE GRAMMAR OF SCIENCE 



forms of things, appears to be merely an instance of that 

 unnecessary dupHcation, which is met by the canon that 

 we ought not to multiply existences beyond what are 

 necessary to account for phenomena.^ 



Turning to the Concrete Sciences, or those which deal 

 with phenomena themselves, Spencer makes a new 

 division into Abstract-Concrete and Concrete Sciences ; the 

 former, he tells us, treat of phenomena " in their elements," 

 and the latter of phenomena " in their totalities." This 

 leads him to associate Astronomy ^lih. Biology and Sociology 

 rather than with Mechanics and Physics. Such a classi- 

 fication may fit some verbal distinction of formal logic, 

 but it is certainly not one that a student of these subjects 

 would find helpful in directing his reading, or which would 

 ever have been suggested by a specialist in either physics 

 or astronomy. But this peculiarity of Spencer's system 

 which separates- Astronomy from its nearest cognates 

 Mechanics and Physics is not its only disadvantage. His 

 third group of Concrete Sciences is again subdivided on 

 what he terms the principle of the " redistribution of 

 force." This he states in the following words : — 



"A decreasing quantity of motion, sensible or insensible, always 

 has for its concomitant an increasing aggregation of matter, and 

 conversely an increasing quantity of motion, sensible or insensible, 

 has for its concomitant a decreasing aggregation of matter." '-' 



Now I have cited this vague principle of the " redis- 

 tribution of force " with the view of showing how 

 dangerous it is for any individual to attempt to classify 

 the sciences even if he possesses Spencer's ability. For 

 this principle has, so far as I am aware, no real foundation 

 in physics, and therefore cannot form a satisfactory 

 starting - point for classifying the Concrete Sciences. 

 According to Spencer, where there is increase of motion 

 there is decreasing aggregation of " matter." Yet we have 

 only to drop a weight to see increase of motion accom- 

 panying increased aggregation of "matter," namely, earth 



^ Entia non stmt multiplicanda praeter necessitatem. See Appendix, 

 Note III. 2 Essays, vol. iii. p. 27. 



