rest? and, how far are we to depend upon this notion? To 

 answer these questions we must consider an example of that which 

 we call knowledge.* \ 



3. I see the candle which burns before me : in other words, 

 I have a consciousness of the existence of such an object. Is 

 there any further proof than this consciousness of its existence? 

 If we are asked how we are assured, by such a reason, that the 

 candle really clo$s exist, \vhat can we reply? Shall we say its 

 existence is necessary to produce the idea? What tells us so? 

 Why the impression which we already have; or our consciousness 

 that it does exist. The only proof therefore which we have of the 

 existence of externals, is the consciousness of their existence. 



4. Is it then true that an external exists? We must reply, that 

 we have a consciousness of its existence; by which we mean that 

 it is true. We cannot otherwise confirm the point, or establish it 

 by higher proofs: for any additional reason which may be assigned 

 to demonstrate its existence, must itself be founded upon this 

 consciousness as its only evidence. For example: we cannot pro- 

 pose, as further proof, that if the candle did not exist, we should 

 not be conscious of it; because this is assuming that it does exist 

 upon the evidence of our consciousness. If, therefore, the con- 

 sciousness of the existence of an object, is the only, and an ade- 

 quate proof of its existence, it follows that all those objects of 

 which we have a consciousness do exist. 



5. But this conclusion does not appear to correspond with 

 our notion of -truth, for a man in his dreams may have precisely the 

 same consciousness as if he were in a theatre: his invention might 

 supply the whole drama, and he might criticise the expression of 

 the actors, the sentiments of the piece; he may be conscious of 

 the presence of a friend to whom he communicates his remarks; 

 he may be conscious of every thing that is false, as if it were a 

 reality; and the only truth is that of which he is unconscious, viz. 

 that the whole is the invention of his own mind. Or, a man in the 

 clearest moonlight, when his senses are awake, may have the 

 strongest perception of the figure of a relation who has been some 

 time dead; a consciousness so unequivocal, as to agitate the 

 functions of the organic life. It is to be presumed, that, upon 

 recollection, a sensible man would impute this perception to a 

 disordered state of his faculties, rather than believe in the reality 

 of such a presence. This evidence of consciousness then, in order 

 to prove an external, seems to be defective; or there appears to 

 be an inconsistency in the credit which is to be assigned to it in 

 different instances. 



6. To take an example of another kind : a man, with an in- 

 cipient amaurosis, will say there are spots, motes, insects, or 



* Throughout this chapter the kind of truth, or belief, referred to, is that 

 relating to positive existences; and where this is not expressed it is to be 

 understood, there is a truth, or belief, with respect to non-existence, which 

 is subsequently spoken of. 



