INTRODUCTION. 



it doubtless does in negative points. But there is a rare 

 property of mind which consists in penetrating the dis- 

 guise of variety and seizing the common elements of 

 sameness ; and it is this property which furnishes the true 

 measure of intellect. The name of" intellect" expresses the 

 interlacing of the general and the single, which is the 

 peculiar province of mind. 1 To cogitate is the Latin co- 

 agitare, resting on a like metaphor. Logic, also, is but 

 another name for the same process, the peculiar work of 

 reason ; for ^0705 is derived from \e<yetv, which like the 

 Latin legere meant originally to gather. Plato said of this 

 unifying power, that if he met the man who could detect 

 the one in the many, he would follow him as a god. 



Laws of Identity and Difference. 



At the base of all thought and science must lie the 

 laws which express the very nature and conditions of the 

 discriminating and identifying powers of mind. These 

 are the so-called fundamental Laws of Thought, usually 

 stated as follows : 



1. The Law of Identity. Whatever is, is. 



2. The Law of Contradiction. A thing cannot loth be 



and not be. 



3. The Law of Duality. A thing must either be or 



not be. 



The first of these statements may perhaps be regarded as 

 a description of identity itself, if so fundamental a notion 

 can admit of description. A thing at any moment is per- 

 fectly identical with itself, and, if any person were unaware 

 of the meaning of the word " identity," we could not better 

 describe it than by such an example. 



The second law points out that contradictory attributes 

 can never be joined together. The same object may vary 

 in its different parts ; here it may be black, and there 

 white ; at one time it may be hard and at another time 



1 Max Miiller, Lectures on the Science of Language, Second Series, 

 vol. ii. p. 63 ; or Sixth Edition, vol. ii. p. 67. The view of the etymolo- 

 gical meaning of " intellect" is given above on the authority of Professor 

 Max Miiller. It seems to be opposed to the ordinary opinion, according 

 to which the Latin intelligere means to choose between, to see a differ- 

 ence between, to discriminate, instead of to unite. 



