CLASSIFICATION. 345 



the logical nature of the operation is, or should be, exactly 

 the same in both cases. We form a class of figures called 

 parallelograms, and we form a general notion of Trilo- 

 bites. 



Science, it has been said at the outset, is the detection 

 of identity, and classification is the placing together, either 

 in thought or in actual proximity of space, those notions 

 or objects between which identity has been detected. Ac- 

 cordingly the value of classification is co-extensive with 

 the value of science and general reasoning. Whenever 

 we form a class we reduce multiplicity to unity, and 

 detect, as Plato said, the one in the many. The result 

 of such classification is to yield generalized knowledge, as 

 distinguished from the direct and sensuous knowledge of 

 particular facts. Of every class, so far as it is correctly 

 formed, the great principle of substitution is true, and 

 whatever we know of one object in a class we also know 

 of the other objects, so far as identity has been detected 

 between them. The facilitation and abbreviation of mental 

 labour is at the bottom of all mental progress. The 

 reasoning faculties of Newton were not different in quali- 

 tative character from those of a ploughman; the difference 

 lay in the extent to which they were exerted, and the 

 number of facts which could be treated. Every thinking 

 being generalizes more or less, but it is the depth and 

 extent of his generalizations which distinguish the philo- 

 sopher. Xow it is the exertion of the classifying and 

 generalizing powers which thus enables the intellect of 

 man to cope in some degree with the infinite number and 

 variety of natural phenomena and objects. In the chapters 

 upon Combinations and Permutations it was rendered quite 

 evident, that from a few elementary differences immense 

 numbers of various combinations can be produced. The 

 process of classification enables us to resolve these com- 

 binations, and refer each one to its place according to 



