THE CLASSIFICATION OF THE SCIENCES 515 



former group deals with the conceptual equivalents of the 

 modes under which the perceptive faculty discriminates 

 objects, the latter with the concepts by aid of which we 

 describe the contents of perception. We have then, to 

 start with, the following division : — 



Perceptions (Sense-Impressions and Stored Impresses). 



Modes of Perception. CoJitents of Perception. 



Abstract Science. Concrete Science. 



Now the two modes in which we perceive things apart, 

 or discriminate groups of sense-impressions, are time and 

 space. Hence Abstract Science may deal with the general 

 relations of discrimination, applying to both time and 

 space without specialising the mode of perception ; or it 

 may refer in particular to space or to time or to their 

 mixed mode, motion. The general relations of discrimi- 

 nation may be either qualitative or quantitative. The 

 former branch is termed Logic, and discusses the general 

 laws by which we identify and discriminate things, or 

 what are frequently termed the laws of thought. A 

 fundamental part of logic is the study of the right use of 

 language, the clear definition and, if needful, invention of 

 terms, — OrtJiology. The object of the present Grammar 

 has been chiefly to show how a want of clear definition 

 has led to the metaphysical obscurities of modern science. 



Both Time and Space lead us at once to the conception 

 of quantity or number, and we thus have a large and 

 important branch of Abstract Science which deals with the 

 laws of quantity. Now quantity may be either discrete 

 and definite, like the numbers of arithmetic 8, 100, '/j,, 

 '^/ , etc., the number of inhabitants of a town, the number 

 of cubic feet in a room ; or it may be continuous and 

 changing with other quantities — for example, like the 

 height of the barometer with the hour of the day, the 

 stature or weight of a man with his age, the position 

 or speed of a body with the time. We thus have a dis- 

 tinction between discrete quantity and quantity capable of 



