I i 



LECTURE V. 



ON ANCIENT AND MODERN SKEPTICS. 



From a system that is simple, intelligible, and satisfactory, adapted to 

 the condition of man, and pregnant with useful instruction, we have now 

 to turn our attention to a variety of hypotheses, that are scarcely in any 

 instance worthy of the name of systems, and which it is difficult to describe 

 otherwise than by reversing the terms we have just employed, and charac- 

 terizing them as complicated, unintelhgible, unsatisfactory; as not adapted 

 , to the condition of man, and barren of useful instruction. 



It is a distinguishing and praiseworthy feature in the Essay on Human 

 •Understanding, that it confines itself to the subject of human understand- 

 ing alone, and that in delineating the operations of the mind, it neither 

 enters into the question of the substance of mind, or the substance of 

 matter ; neither amuses us with speculations how external objects com- 

 municate with the senses, or the senses with the mental organ. It builds 

 altogether upon the sure foundation of the simple fact, that the senses 

 are influenced, and that they influence the mind ; and as, in the former 

 case, it calls the cause of this mfluence external objects, so in the latter 

 case it calls the eflfects it produces internal ideas. Of the nature of these 

 objects it says httle, but of their substantive existence ; of the nature of 

 these ideas it says little, but of their truth or exact correspondence with 

 the objects that excite them ; its general view of the subject being re- 

 ducible to the two following propositions : — 



First, that as objects are perceivable at a distance, and bodies cannot 

 act where they are not, it is evident that something must proceed from 

 them to produce impulse upon the senses, and that the motion hereby ex- 

 cited, may be thence continued hy the nerves, or connecting chain, to tlie 

 Brain or seat of sensation, so as to produce in our minds the particular 

 ideas we have of them.* 



And, secondly, that the ideas thus produced, so far from being images 

 or pictures of the objects they represent, have no kind of resemblance to 

 them, except so far as relates to their realquahties of solidity, extension, 

 figure, motion, or rest and number. t 



Thus far, and thus far only, does the author of the Essay on Human 

 Understanding indulge in a digression into physical science ; and even for 

 this he feels it necessary to offer an apology to his reader : " I hope," says 

 be, " I shall be pardoned this little excursion into natural philosophy, it 

 being necessary in our present inquiry."| 



For myself I am glad he did not proceed farther, and should have been 

 still more satisfied if he had not proceeded even so far ; for the subject 

 proves itself, even in his hands, to be inexplicable ; and if he be here found 

 to evince some degree of obscurity, it is only, perhaps, because it is not 

 possible to avoid it. Of the primary or real qualities of bodies, as he 

 denominates them, we know but little ; and it is probable that Mr. Locke 

 has enumerated one or two under this head that do Jiot properly belong 

 ito the list. And although it is not difficult to determine his meaning where 



* Essay on Hum. Underst. Book ii. ch. viii. § 12. 

 t Ibid. §15. t Ibid. §22. 



