ABSTRACTION. 201 



ceptions, to be subservient to Induction, must be " clear" and 

 " appropriate." 



If the conception corresponds to a real agreement among 

 the phenomena; if the comparison which we have made of a 

 set of objects has led us to class them according to real resem- 

 blances and differences ; the conception which does this can- 

 not fail to be appropriate, for some purpose or other. The 

 question of appropriateness is relative to the particular object 

 we have in view. As soon as, by our comparison, we have 

 ascertained some agreement, something which can be predicated 

 in common of a number of objects; we have obtained a basis 

 on which an inductive process is capable of being founded. 

 But the agreements, or the ulterior consequences to which 

 those agreements lead, may be of very different degrees of 

 importance. If, for instance, we only compare animals 

 according to their colour, and class those together which are 

 coloured alike, we form the general conceptions of a white 

 animal, a black animal, &c., which are conceptions legitimately 

 formed ; and if an induction were to be attempted concerning 

 the causes of the colours of animals, this comparison would 

 be the proper and necessary preparation for such an induction, 

 but would not help us towards a knowledge of the laws of 

 any other of the properties of animals : while if, with Cuvier, 

 we compare and class them according to the structure of the 

 skeleton, or, with Blainville, according to the nature of their 

 outward integuments, the agreements and differences which 

 are observable in these respects are not only of much greater 

 importance in themselves, but are marks of agreements and 

 differences in many other important particulars of the struc- 

 ture and mode of life of the animals. If, therefore, the study 

 of their structure and habits be our object, the conceptions 

 generated by these last comparisons are far more " appropriate" 

 than those generated by the former. Nothing, other than 

 this, can be meant by the appropriateness of a conception. 



When Dr. Whewell says that the ancients, or the school- 

 men, or any modern inquirers, missed discovering the real law 

 of a phenomenon because they applied to it an inappropriate 

 instead of an appropriate conception ; he can only mean that 



