( 6icg ) 
but, weretheyall but twofiz.s, it would be a vtiy puzlmg 
phccnomenon. And I fliould thiok it asunaccouotablej if the 
feveral parts or corpufcles, of which a ftiining body confifts, 
which muft bcfuppos'd of various figures, fizes and morions, 
ftiould imprcfs but two forts of motion oo the z&yictm Mth f 
real medium^ or any other way beget but two forts of Kays. 
But to examinCjhow Colors may be tiniphitidhypotheticaUy 
belides my purpofe, I never intended to (bew^ wherein con- 
fifts the Nature and DifFercnce of Golors^but only to (hew, that 
defaUo they arc Original and Immutable qualities of the Rays 
which exhibjt them ^ and to leave it to others to explicate by 
Mechanical Hypothefes the Natyre and Difference of rhofe 
qualities: which I take to be no difficuk matter. But I would 
not be undcrfiood, as if their Difference conlifted in the Dif- 
ferent Refrangibility of thofc rays\ for,that different Refran- 
gibility conduces to their produftidn no otherwife, than by 
fcparating the Rays whofe qualities they are. Whence it 
that the fame Rays exhibit the fame Colors wheo feparated by 
any other means 5 as by their different ReflexibiUty^ a quality 
not yet dilcourfed of. 
In the next particular, where would (hewj that it is not 
ncceflary to mix all Colors for the produftion of finite the 
mi}Lturto( Tel/oTP) Green s^nd Blew^ without Red and Ftolety 
which he propounds for that ertd^ will not produce ^FAi/e,but 
Green 5 and thebrighteft part of the Yellow will afford no o- 
ther colour but Yellow^if the Experiment be made in a room 
well darko'd^as it ought h becaufe the Colour'd light is much 
weaken'd by the Rcflexionj and fo apt to be diluted by the 
mixing of any other fcaitering light. But yet there is an Ex- 
periment or two mentioned in my Letter in the Trar^fiSions 
Nnntb^iS^ by which I have produced White out of two colors 
alone,and that varioufly, as out of Orange and ^fullBletiPy and 
out of Red and pale Bierp^ and out ofTellow and Violet^ as alfo 
out of other pairs of Intermediat colors. The moft conveni- 
ent Experiment for performing this,was that of cafting the co- 
lorsofoncPrifmeuponthofeofanotherj after a due manner. 
But what N. can deduce from hence, I fee not. For the two 
colors were compounded of all others, and fo the rcfulting 
White^ ( to fpeak properly J was compounded of them all, • 
Qjjq qqq 3 and 
