348 THE PRINCIPLES OF SCIENCE. 



Professor Huxley has defined the process of classifica- 

 tion in the following terms b . ' By the classification of any 

 series of objects, is meant the actual or ideal arrange- 

 ment together of those which are like and the separation 

 of those which are unlike ; the purpose of this arrange- 

 ment being to facilitate the operations of the mind in 

 clearly conceiving and retaining in the memory the cha- 

 racters of the objects in question/ 



This statement is doubtless correct, so far as it goes, 

 but it does not include all that Professor Huxley himself 

 implicitly treats under classification. He is fully aware 

 that deep correlations, or in other terms deep uniformi- 

 ties or laws of nature, will be disclosed by any well 

 chosen and profound system of classification. I should 

 therefore propose to modify the above statement, as fol- 

 lows : ' By the classification of any series of objects, is 

 meant the actual or ideal arrangement together of those 

 which are like and the separation of those which are 

 unlike, the purpose of this arrangement being, primarily, 

 to disclose the correlations or laws of union of proper- 

 ties or circumstances, and, secondarily, to facilitate the 

 operations of the mind in clearly conceiving and retain- 

 ing in the memory the characters of the objects in 

 question.' 



Multiplicity of Modes of Classification. 



In approaching the question how any given group 

 of objects may best be classified, let it be remarked that 

 there must generally be an unlimited number of modes 

 of classifying any group of objects. Misled, as we shall 

 see, by the problem of classification in the natural sciences, 

 philosophers often seem to think that in each subject 

 there must be one essentially natural classification which 



b ' Lectures on the Elements of Comparative Anatomy,' 1864, p. i. 



