5. WhicenefsiD all refpeds like that of rhe Sun^s imme^i^ 
ate light cannot be compounded of fimple colors without an 
indefioite variety of them. For to fuch a cotnpofitioQ there 
are requifite rays indued with all the iodefioite degrees of rc 
frangibility^by Pr(7/?. I. And thofe infer as many fimple colors, 
by D^/. Land 3. and Fr<?/?, 2, aod 3. 
To make thefe a little plainer J have added alio the Pro- 
pofitions that follow, 
6. The rays of light do not aft on one aoother in paffing 
through the fame Medium. This appears by feveral paffiges 
ia thtTrafifa3ions pag. s^97^ 50p8,;ioo, and 5101. aod is 
capableof further proof . ' 
7. The rays of light fufFcr not any change of their qualicies 
from refraction. 
8. Nor afterwards from the ad j iceiit quiet TheTe 
two Propofitions aremanifcftje facto in homogen^al light, 
whofecolor and refrangibility isnot at all changeable cither 
by refraftion or by fhe contermiaation of a q\im Medium^ 
Aod as for hcterogeneal lights it is but an aggregate of feveral 
forts of homogeneal light, no one fort of which fuflers any 
more alteration than if it were alone, becaufe the rays aft not 
on one another, by Pr^?/^, 6. And therefore the aggregate caa 
fufler none. Thefe two Pr^?/^^/i(?»/alfo might be further pro- 
ved apart by^xperiments, too long to be here defcribe4 
9. There can no homogeneal colors be educed out of light 
by refraftion which were not commixt in it before ; Becaufej 
by Prop, j^and 8,Refra(Si:ion changeth not the qualities ofthe 
rays, but only feparates thofe which have divers qualities 5 by 
meanes of thtir different Refrangibility* 
10. The Sun's light is an aggregate of an indefiaite varie« 
ety of homogeneal colors 5 by Prop, i, ^^and 0. And hence 
it is, that I call homogeneal colors alfo primitive ororiginaL 
And thus much concerning Colors, 
Monfieur N. has thought fit to iofiouate, that the aberration 
of rays ( by theirdifferent refrangibility) is not fo confide- 
rable a difad vantage in glafles as I feemed to be willing to 
make men believejwhen I propounded concave mirrors as the 
only hopes of perfeciiog Telefcopes. But if he pleafe to take 
his pen and compute the errors of a Glafs and Spcculucn that 
Ooo 000. collet 
