346 ON HUMAN UNDERSTANDING. 



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 ACA- 

 DEMY. 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 ; be- 

 lieving 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 produce, though he admitted an external 

 world of some kind or other. And upon being reminded, by one of his scho- 

 lars, who had a wish to please him, that the only thing which Socrates de- 

 clared he was certain of was his own ignorance, he immediately replied, that 

 Socrates had no right to say even that for that no man could be certain of 

 any thing. It was against this unhappy madman, though, in other respects, 

 like Pyrrho, excellent and accomplished 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 so 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, 

 Must 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 aloae 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 1 Absurd the thought ! 

 For every sense a separate function boasts, 

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

 Or hot, or cold, to its appropriate sense 

 Alone appeals. The gaudy train of hues, 

 With their light shades, appropriate thus, alike 

 Perceive we ; tastes appropriate powers possess ; 

 Appropriate sounds and odours ; and hence, too, 

 One sense another ne'er can contravene, 

 Nor e'en correct itself; since, every hour, 

 In every act, each claims an equal faith. 



E'en though the mind no real cause could urge 

 Why what is square when present, when remoX 

 Cylindric seems, 't were dangerous less to adop k 

 A cause unsound, than rashly yield at once 

 All that we grasp of truth and surety most; 

 Rend all reliance, and root up, forlorn, 

 The first firm principles' of life and health. 

 For not alone fails reason, life itself 

 Ends instant, if the senses thou distrust, 

 And dare some dangerous precipice, or aught 

 Against warn'd equal, spurning what is safe. 

 Hence all against the senses urg'd is vain ; 

 Mere idle rant, and hollow pomp of words. 



As, in a building, if the first lines err, 

 If aught impede the plummet, or the rule 

 From its just angles deviate but a hair, 

 The total edifice must rise untrue, 

 Recumbent, curv'd, o'erhanging, void of grace, 

 Tumbling or tumbled from this first defect, 

 So must all reason prove unsound, deduc'd 

 From things created, if the senses err/* 



* Denique, nihil sciri si quis putat, id quoque nescit 



An sciri possit, &c. Lib. iv. 471. 

 The passage is too long for quotation, and the reeilor may easily tarn to it at his leinure. 



