PEOE. EEBEIEE ON KNOWING AND BEING. 107 



then (I answer) the attempt of the Institutes must be abandoned as 

 hopeless ; just as it would have been hopeless for Euclid to attempt to 

 make out a single necessary proposition respecting the circle, if he 

 had not first fixed what a circle is. One would stare who should be 

 asked to demonstrate that the object of X T Z must always be self- 

 cum-alio : but it would not be more unreasonable to demand this of 

 him, than to ask him to prove that the object of knowledge must be 

 self-cum-alio, the nature of knowledge beiug undetermined. 



Professor Ferrier was thoroughly aware of this. He saw that a 

 solution of the question : What is knowledge ? is the prime condi- 

 tion of a system of necessary propositions respecting knowledge, and 

 indeed must contain in itself the whole concentrated essence of an 

 Epistemology. Has he then answered the question ? He thinks 

 that he has. But his answer is in reality none. It is not a definition 

 of the matter needing to be defined, but a statement regarding a 

 different point altogether. Let us consider what is implied in a 

 definition of knowledge. This is brought out with great clearness in 

 the Theaetetus, a dialogue of Plato, which our author quotes and com- 

 ments upon very felicitously. The interlocutors are Socrates, and a 

 young man called Theaetetus. Socrates puts the question : " "What 

 " does science (knowledge) appear to you to be" ? Theaetetus 

 answers, " It appears to me that sciences are such things as one may 

 " learn from Theodoras : geometry, and the others which you just 

 "now enumerated." To which Socrates with exquisite raillery re- 

 joins, " Nobly and munificently, answered my friend, when asked for 

 one thing, " you give many :" adding, " The question asked was not 

 " this : of what things there is science ; for we did not enquire with a 

 " view to enumerate them, but to know what science itself is." He 

 illustrates his meaning by supposing a person to be asked, What is 

 clay ? The person would answer, not by enumerating the different 

 kinds of clay : potters' clay, ovenbuilders' clay, brickmakers' clay, and 

 the like, but by stating what is common to all clay — that it is earth 

 mixed with water. In like manner, it is no reply to the question, 

 What is knowledge, to specify various kinds of knowledge, the know- 

 ledge of geometry, the knowledge of music, &c. ; but the thing on 

 Avhich information is desired, is : What common element belongs to all 

 cognition ? — " Come," said Socrates to his young friend, " endeavour 

 " to designate many sciences (kinds of knowledge) by one notion " 

 He therefore who would explain what knowledge is, must, if Plato 

 has reasoned well, show us the one notion dcsignative of the many 

 varieties of knowledge. Has Professor Perrier done this? Ho 

 has not. He thinks that he has. In the opening proposition of tho 



