of the Physical Sciences. 463 



wide and metaphorical sense. In this application it was very 

 early contrasted with artificial creation ; but in later times, per- 

 haps under the influence of Plato, the Greek derivatives have 

 more emphatically suggested a contrast with things supposed to 

 be above growth, not below it, with things eternal. Hence the 

 antithesis of moral and physical, even mental and physical. 



It is in the first application that we speak of physiology, and 

 perhaps of natural history ; all the other terms above mentioned 

 belong to the second application. 



Our materials would be most economically turned to account 

 by using the word natura in the second and wider application, 

 and phy'sis in the first and narrower one. But there would be 

 something arbitrary in the selection, and it would be the formal 

 abandonment of perhaps the oldest generalization in philosophy. 



The only practicable consistent system would consist in using 

 both natura and phy'sis in the wider application ; to preserve, 

 that is, the phrases physical and natural science or knowledge, and 

 to find other terms for the subdivisions. But then what are we 

 to do with physiology ? It would probably be necessary to keep 

 biology, although, as it ought properly to mean the science of 

 lives, lifetimes, or livelihoods, it is not very good Greek for the 

 science of life ; zoology has been appropriated as the science of 

 zoa, animals. But the main division of the province was ex- 

 pressed in old times by the words empsycha and dpsycha, corre- 

 sponding to our correct but less manageable adjectives organic 

 and inorganic. I see no good reason against empsychology and 

 apsychology : the words are long, but easily pronounced and 

 easily contrasted by their accentuation. For a different reason, 

 apsychology might not be currently used — namely, because it is a 

 negative word; it would not, in fact, be necessary to use it 

 so often. 



Apsychology would approximately coincide with natural phi- 

 losophy. It remains to consider its principal species, physics. 

 This term is the easiest replaced of all. I propose a reform 

 which would have the advantage of rescuing another word from 

 a sense in which I contend it is used improperly at present. It 

 is not quite true, as I shall show, that this section of physical 

 science is distinguished by its mathematical treatment. But 

 what does distinguish it is the idea of force conceived as funda- 

 mentally the same throughout it. I would therefore call it dyna- 

 mics. That dynamics is used already in a more restricted sense 

 in opposition to stattics, is a reason in favour of the change ; for 

 it is wrongly so used. The idea of force is common to statics 

 and " dynamics •" what distinguishes " dynamics " is the idea of 

 motion. It should be called cinetics. This word may seem 

 tainted with the heresy condemned by Sir John Herschel at the 



