38 ANTIENT MET APH YSICS. Book I. 



two may be ranked among the principles of the univerfe; for of one 

 and Diultitiide^ Jamentjs and divtrjity^ likenefs and unlikmefs^ equality 

 and inequality^ the "juholc ot things is compofed, makh^g that * renim 

 * co7icordta dijcors^ of which Horace fpcaks. 



hWfubfiances have accidents ; for every thing in nature acls or fuf~ 

 /ersy and has. quahties by which it a^s oxjuffers, 



Thefe accidents are predicated of fubftances -either kx6' d-jjp, or kxt» 

 »-v^ej€««xaf, words which occur very frequently in Ariftotle's writings, 

 and therefore ought to be explained. An accident is xx6' kvro of a fub- 

 JlancCy when it is neceflary to that fubftance, fo as the fubftance can- 

 not exift without it. This is the cafe when it is deduced by neceflary 

 confequence from the definition of a fubtlance ; for, if it be includejd 

 in the definition, then it is not y.cS «yr«, but part of the to t. «v «»«», or x*- 

 y«5 T„? c^^^xi'. — That is, in Englifh, It is not an ejfential property of the 

 fubftance, but the ejfence^ or part of the ejjence of the fubftance. 



In this manner, to have the three angles equal to two right angles, 

 is an eflential property of a triangle; whereas, being bounded by three 

 lines, is the eflence of a triangle. It may be obferved, that a proper- 

 ty may be neceflfary to a thing, and yet not be ^ao'ii-T* of that thing. 

 For example, having three angles equal to two Tight, is a neceflfary 

 property of an ifojceles triangle, yet not kx^ ii^ro of it, but of a triangle; 

 becaufe it does not refult from the definition of an ijofceles triangle, 

 like the property of having two angles at the bafe equal, but from the 

 definition of a triangle: On the other hand, an accident is kxtx <rvuZi^^KOi 

 of any fubftance, when it may, or may not, accoapany the fubftance, 

 and vet the fubftance continue the. lame; lo that fuch an accident is 

 3&vha[, in common language, is called accidental to a thing *. 



Thefe, 



* Arlflct. Mctaphyf lib i^- c?p \Z. anH 30. And, in the fitft chapter of the 

 ■firfl Lcci> oi mcU] i.yljc&, he givti ».n txan.plt oi a thing being y.u.ix iry^^ii'fc^jjx)?, or by 



accuitiit. 



