286 ELEMENTS OF SCIENCE 



all apprehension of them. A horse, and our idea of, 

 and name for, a horse, remain the same, whatever may 

 be the direction of our mind in considering such things, 

 and the same is the case with regard to the quality 

 " quadrupedal." As we have seen,* living things are 

 arranged by science in a definite classification. Therein 

 the creatures which constitute a genus are always the 

 same, and the terms "genus" and "species" can never 

 change places. But there are, in logic, certain things and 

 names, which, instead of being constant, change accord- 

 ing to the direction in which the mind is turned as it 

 regards them, and their mode of classification changes 

 correspondingly, and in this way classificatory groups 

 may change in position and value. Thus we may think 

 of " Jews," as a group. Then " Jews of Middlesex," 

 " those of Essex," &c. &c., will be minor groups subordi- 

 nate to the larger and dominant one "Jews." But we 

 may also first think of " Jews of Middlesex," and then 

 of those which are " reformed," and those which are 

 " unreformed," which will then constitute subordinate 

 groups, while the group " Jews of Middlesex " will change 

 from being, as before, subordinate, and become the larger 

 and dominant one. Similarly, the group " Jews " will 

 change from a dominant group into a subordinate one, 

 if we think of the larger group, "European." Now 

 these conceptions of dominant and subordinate groups 

 are respectively characterised by certain differences. 

 Thus the difference between " Jews " generally and 

 " those of Middlesex," consists in the latter inhabiting 

 that county. 



There are also certain qualities which are essential, or 

 proper, to objects, and others which belong to them only 



* See ante, p. 190. 



