Cliap. VIII. ANTIENT METAPHYSICS. 141 



and exercife; and leaving only what of.vlrtue can be got by teaching 

 and inftrudion. Another confequence of this opinion is, that if virtue 

 be fcience, a man who has the fcience or knowledge of v/hat Jaf- 

 tice, for example, is, or Temperance, muft of confequence be juft or 

 temperate; in the fame manner as a man who underftands mathema- 

 tics or metaphyfics, is a mathematician or metaphyfician. But this 

 is certainly not true ; and the error lies in making a theoretical kS- 

 ence of what is truly a practical art, as much as painting, mufic, 

 and the like: And it would be as abfurd to fay, that a man can be 

 virtuous by fcience merely, as that he can be a painter. Next came 

 Plato, who improved much upon his Mailer's dodrine of' morals 

 dividing the foul, very properly, into three parts, and affigning to 

 each of them its proper virtues. But he erred in mixing, with tne 

 dodrine of morals, metaphyfical fpeculations about the general idea 

 of Good, which, fays Ariftotle, was not proper, becaufe not belong- 

 ing to his fubjed. And this is the only fault he finds with the Ethics 

 of his mafter ; and in this refped only he feems to f^ive the prefer- 

 ence to his own. But, upon inquiry, it will be found that there are 

 many more defeds in Plato's fyftem, and many more excellencies 

 in that of his fcholar. For, in xhtfirjl place, Plato explains the vir- 

 tues, as he does almoft every thing elfe, by a fimiUtude: And his 

 whole dodrine of luhics is a comparifon betwixt a well conftituted 

 commcnwealth and a virtuous mind ; confounding thereby the two 

 fciences of morals and politics, which, though they be branches of 

 the fame fcience, known by the name, as it has been obferved " of 

 pontics, taken in its larger acceptation, yet, for the fake of method 

 and perfpicuity, ought be treated of feparately ; becaufe, although 

 they have many things in common, and though the one be in a 

 great meafure the foundation of the other, yet they have alfo many 

 things different, ido. What Plato fays of one of the prime virtues, 

 namely, Juftice, is much too general and very imperfed; for he 

 feems only to treat of that virtue, called Juflice, in a general kw^^, 



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