in.] PROPOSITIONS. 39 



All definitions are necessarily of this form, whether the 

 objects defined be many, few, or singular. Thus we may say, 



Common salt = Sodium chloride. 



Chlorophyl = Green colouring matter of leaves. 



Square = Equal-sided rectangle. 



It is an extraordinary fact that propositions of this 

 elementary form, all-important and very numerous as they 

 are, had no recognised place in Aristotle's system of Logic. 

 Accordingly their importance was overlooked until very 

 recent times, and logic was the most deformed of sciences. 

 But it is impossible that Aristotle or any other person 

 should avoid constantly using them ; not a term could be 

 defined without their use. In one place at least Aristotle 

 actually notices a proposition of the kind. He observes 

 " We sometimes say that that white thing is Socrates, or 

 that the object approaching is Callias." 1 Here we certainly 

 have simple identity of terms ; but he considered such 

 propositions purely accidental, and came to the unfortunate 

 conclusion, that " Singulars cannot be predicated of other 

 terms." 



Propositions may also express the identity of extensive 

 groups of objects taken collectively or in one connected 

 whole ; as when we say, 



The Queen, Lords, and Commons = The Legislature of 



the United Kingdom. 



When Blackstone asserts that " The only true and natural 

 foundation of society are the wants and fears of individuals," 

 we must interpret him as meaning that the whole of the 

 wants and fears of individuals in the aggregate form the 

 foundation of society. But many propositions which 

 might seem to be collective are but groups of singular 

 propositions or identities. When we say " Potassium and 

 sodium are the metallic bases of potash and soda," we 

 obviously mean, 



Potassium = Metallic base of potash ; 



Sodium = Metallic base of soda. 



It is the work of grammatical analysis to separate tb. 

 various propositions often combined into a single sentence 

 Logic cannot be properly required to interpret the forms 

 and devices of language, but only to treat the meaning 

 when clearly exhibited. 



1 Prior Analytics, i. cap. xxvii. 3. 



