A TREATISE 



1 i. ........ >. .. 



3. exactly vvith*^r*/?rr/f.f principles, and fbJlovveth evidently out 



The former o f j lls definitions of light, and of colours. And for lumming 



doarinc con- ^^ ,r e nerallfentiments of mankind in making his Logical! 

 firmed by An- , r ,, . P _ . . . L j -n j 



ftotles autho- definitions, I thmke no body will deny his being the greateft 

 rity,reafcn,in<i Mailer that ever was. Hee defineth light to be *tlw Dtapftam : 

 experience. which we may thus explicate. It is that thing, which maketh a 

 body that hath an aptitude or capacity of being feene quite 

 through it in every interior part of it, to be actually feene quite 

 through, according to that capacity of it. And hee defineth 

 colour to be, Tke terme or tnding #/ 4 diapkMtsfK My : the mea- 

 ning whereof is : that colour is a thing which maketh a diapha- 

 nous body to reach no further j or that colour is the caufe why 

 a body is no further diaphanous, then untill where it beginnethf 

 or that colour is thereafon, why we can fee no further then to 

 fuch a degree, through or into fuel a body. 



Which definition fitteth moft exactly with the thing it i- 

 veih us the nature of. For it is evident, that when we fee a body, 

 the body we fee^hindereth us from feeing any other, that is in a 

 ftraigbt line beyond it; And therefore it cannot be denyed, but 

 that colour terminateth,andendeth the diaphaneity of a body, 

 by making it felfebe feene. And all men do agree in conceiving 

 this , to be the natnre of colour ; and that it is a certaine dii- 

 pofition of a body , whereby that body commeth to be feene. 

 On the other fide^nothing is more evident, then that to have u$ 

 fee a body , Jight mult reach from that body to our eye. Then 

 adding unto this what Ariftot Je teacheth concerning the pro- 

 duction of feeing : which he fayth is made by the action of the 

 fecne body upon oar fcnfe : itfolloweth that'thc object muft 

 vyorkeupon oar ienfe, either by %ht, or at the Jea/t with 

 li^ht ; for light rebounding from the object round about by 

 ttraight lines,iome part of it mufr needs come from the ob/ec> 

 to our eye. Therefbre,by how much an object fendeth more 

 light unto onr tye^by fb much,, L that object worketh more upon 

 it. 



Now leebig that divers objects do fend light in divers man- 

 ner* to our eyCjaecordij^ to the divers nature* of thofe objects 

 in regard of hardnefle, den/5ty , and littleneffc of parts: we 

 muft agree that fuch bodies do worke diverfly , and do make 

 different motions or imprefftoni upon onr eyerand confequent- 



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