TWO THEORIES OF KNOWLEDGE 41 



typified the eternal forms of things the essential 

 constituents of the real world. Knowledge was 

 possible because there were such eternal forms 

 or ideal elements the archetypes of which the 

 sify were the counterparts and representations. 



Knowledge, Plato held, was concerned solely 

 with these eternal forms, not with sensation at all. 

 The sensible world was in a state of constant flux 

 and could not be the object of true science. Its 

 apprehension was effected by a faculty or capacity 

 (Republic, v. 478-79) midway between Knowledge 

 and nescience to which he applied the term $o|a, fre- 



W"' 



quently translated opinion, but which in this con- 

 nection would be much more accurately rendered, 

 ^sensible impression, or even perception. At any 

 rate, the term opinion is a very unhappy one, and 

 does not convey the true meaning at all, for no 

 voluntary intellective act on the part of the subject 

 was implied by the term. Now intelligence in con- 

 structing a scheme of Knowledge is active. The 

 ideas are the instruments of this activity. 



Plato's doctrine of ideas was probably designed 

 or conceived by him as affording an explanation 

 also of the community of Knowledge. He empha- 

 sised the fluent instability of the sensible impression, 

 and as we have already pointed out, sensation in 

 itself labours also under this drawback that it 



