TERMINOLOGY AND NOMENCLATURE. 255 



their inventors, until aptly-selected words or phrases have, as 

 it were, nailed them down and held them fast. 



4. Of the three essential parts of a philosophical 

 language, we have now mentioned two : a terminology suited 

 for describing with precision the individual facts observed ; 

 and a name for every common property of any importance or 

 interest, which we detect by comparing those facts : including 

 (as the concretes corresponding to those abstract terms) names 

 for the classes which we artificially construct in virtue of those 

 properties, or as many of them, at least, as we have frequent 

 occasion to predicate anything of. 



But there is a sort of classes, for the recognition of 

 which no such elaborate process is necessary ; because each 

 of them is marked out from all others not by some one 

 property, the detection of which may depend on a difficult 

 act of abstraction, but by its properties generally. I mean, 

 the Kinds of things, in the sense which, in this treatise, has 

 been specially attached to that term. By a Kind, it will be 

 remembered, we mean one of those classes which are distin 

 guished from all others not by one or a few definite properties, 

 but by an unknown multitude of them : the combination of 

 properties on which the class is grounded, being a mere index 

 to an indefinite number of other distinctive attributes. The 

 class horse is a Kind, because the things which agree in 

 possessing the characters by which we recognise a horse, 

 agree in a great number of other properties, as we know, and, 

 it cannot be doubted, in many more than we know. Animal, 

 again, is a Kind, because no definition that could be given of 

 the name animal could either exhaust the properties common 

 to all animals, or supply premises from which the remainder 

 of those properties could be inferred. But a combination of 

 properties which does not give evidence of the existence of any 

 other independent peculiarities, does not constitute a Kind. 

 White horse, therefore, is not a Kind ; because horses which 

 agree in whiteness, do not agree in anything else, except the 

 qualities common to all horses, and whatever may be the 

 causes or effects of that particular colour. 



