ON HUMAN UNDER^fANDING, 



lueiit-^the external world becomes a mere show — and there is no truth 

 or solidity in any thing. He was not able to prove the solidity of the 

 elementary atoms of matter. He hence doubted of every thing ; advised 

 all the world to do the same ; and established a school for the purpose of 

 inculcating this strange doctrine. In every other respect he v/as a man of 

 distinguished accomphshments, and so highly esteemed by his country- 

 men, as to have been honoured with the dignity of chief priest, and ex- 

 empted from public taxation. But, to such a formidable extreme did this 

 disease of skepticism carry him, that one or more of his friends, as we are 

 gravely told in history, were obliged to accompany him wherever he went, 

 that he might not be run over by carriages, or fall down precipices. Yet 

 he contrived, by some means or other, to live longer than most men of 

 caution and common sense ; for we find him at last dying of a natural 

 death, at the good old age of ninety. 



Arcesilas was one of the successors to Plato in the academic chair, and 

 founder of the school that has been known by the name of the Middle 

 Academy. Plato, in his fondness for intellectual ideas, those creatures 

 of his own imagination, had always given a much greater degree of credit 

 to their testimony than to that of the objects which compose the material 

 world ; believing that the mind was less likely to be imposed upon than 

 the external senses. And with so much zeal was this feeling or prejudice 

 followed up by Arcesilas, that he soon began to doubt, and advised his 

 scholars to doubt also, of the reality of every thing they saw about them ; 

 and at length terminated his doubts in questioning the competency of 

 reason itself to decide upon any evidence the external senses might pro- 

 duce, though he admitted an external world of some kind or other. And 

 upon being reminded, by one of his scholars, who had a wish to please 

 him, that the only thing which Socrates declared he was certain of was 

 bis own ignorance^ he immediately replied, that Socrates had no right to 

 say even that — for that no nmn could be certain of any thing. It was 

 against this unhappy madman, though in other respects, like Pyrrho, an ex- 

 cellent and accomphshed scholar, that Lucretius directed those forcible 

 verses in favour of the truth and testimony of the senses, as the only genuine 

 means of acquiring knowledge, which have been so often referred to, and 

 , f;o warmly commended in the controversy of the present day ; 



Who holds that naught is known, denies he knows 

 E'en this, thus owning that he nothing knows: 

 With such I ne'er could reason, who, with face 

 Retorted, treads the ground just trod before. 



Yet grant e'en this he knows ; since naught exists 

 Of truth in things, whence learns he what to know. 

 Or what not ^know ? What things can give him first 

 The notion crude of what is false or true ? 

 What prove aught doubtful, or of doubt devoid ? 



Search, and this earliest notion thou wilt find 

 Of truth and falsehood, from the senses drawn. 

 Nor aught can e'er refute them ; for what once, 

 By truths oppos'd, their falsehood can detect, 

 Musi claim a trust far ampler than themselves. 

 "Yet what, than these, an ampler trust can claim ; 

 Can reason, born, forsooth, of erring sense, 

 Impeach those senses whence alone it springs ? 

 And which, if false, itself can ne'er be true. 

 Can sight correct the ears ? Can ears the touch 

 Or touch the tongue's fine flavour ? Or, o'er all 

 Can smell triumphant rise V Absurd the thought I 

 For every sense a separate function boasts, 

 A power prescrib'd ; and hence, or soft, or hard, 

 Or hotj or cold, to its appropriate sen*e 



