600 Db whewell, of the intellectual powers 



" You have explained it well, said I. And now consider the four sections (of the line) of 

 which we have spoken, as corresponding to four affections in the mind. Intuition, the highest ; 

 Conception, the next; the third, Belief; and the fourth, Conjecture (from likenesses); and 

 arrange them in order, so that they may have more or less of certainty, as their objects have 

 more or less of truth*. 



'• I understand, said he. I agree to what you say, and 1 arrange them as you direct." 



And so the Sixth Book ends : and the Seventh Book opens with the celebrated image of 

 the Cave, in which men are confined, and see all external objects only by the shadows which 

 they cast on the walls of their prison. And this imperfect knowledge of things is to the true 

 vision of them, which is attained by those who ascend to the light of day, as the ordinary know- 

 ledge of men is to the knowledge attainable by those whose minds are purged and illuminated 

 by a true philosophy. 



Confining ourselves at present to the part of Plato's speculations which we have men- 

 tioned, namely, the degrees of knowledge, and the division of our knowing faculties, we may 

 understand, and may in a great degree accept, Plato's scheme. We have already (in the 

 preceding papers) seen that, by the knowledge of real things, he means, in the first place, the 

 knowledge of universal and necessary truths, such as Geometry and the other exact sciences 

 deal with. These we call sciences of Demonstration ; and we are in the habit of contrasting 

 the knowledge which constitutes such sciences with the knowledge obtained by the Senses, by 

 Experience or mere Observation. This distinction of Demonstrative and Empirical knowledge 

 is a cardinal point in Plato's scheme also ; the former alone being allowed to deserve the name 

 of Knowledge, and the latter being only Opinion. The Objects with which Demonstration deals 

 may be termed Conceptions, and the objects with which Observation or Sense has to do, how- 

 ever much speculation may reduce them to mere Sensations, are commonly described as Things. 

 Of these Things, there may be Shadows or Images, as Plato says; and as we may obtain a certain 

 kind of knowledge, namely Opinion or Belief, by seeing the Things themselves, we may obtain an 

 inferior kind of Opinion or Belief by seeing their Images, which kind of opinion we may for the 

 moment call Conjecture. Whether then we regard the distinctions of knowledge itself or of 

 the objects of it, we have three terms before us. 



If we consider the kinds of Knowledge, they are 



Demonstration: Belief: Conjecture: 



If the objects of this knowledge, they are 



Conceptions : Things : Images. 

 But in each of these Series, the first term is evidently wanting : for Demonstration supposes 



The Diagram , as here described, would be this ; , 



Plato supposes the whole, and each of the two parts, to be divided in the same ratio, in order that the analogy of the 

 division in each case may be represented. 



