($0^0 J 
there would be little or no difference between Us . For he 
grants, that without any relpect to a diflferent Incidence of 
rays there are different Refraftions 5 but he would have it ex- 
plicated, not by the different Refrangibility of feveralRays, 
but by the Splitciiig and Rarefying of ethereal puifes. fle 
p2Lms my third, fourth and ^xth Propofitions j the fenfe of 
which is. That Un^compounded Colors are unchaDgeable^aad 
that Compounded ones are changeable only by refolving them 
into the e^ors^ of which they are compounded i and thac all 
iheChangeSj which can be wrought in Colours, are effcdled 
only byvariouQy mixing or parting them • But he grants theni 
on coddition that I will explicate Colors by the two fides of a 
fplitptilfe, and fb make but two Jpecies of them, accounting 
all other Colors in the world to be but various degrees and di- 
lutings of thole two. And he further grants, that IVhitenejfe is 
produced by the Convention of all Colors ; but then I muft ah 
low it to be not only by Mixture of thofe Colors, but by a far- 
trher Uniting of the parts of theRay tflppofed to be formerly 
Iplit. 
If I would proceed to examine rhefe his Explications, I 
fhinkic would be no difBcult matter to fhew, that they are not 
only infiifficient^hnt in Tome refpects to me Cat Ifeaft) un-inteEh 
gible^ For^ though it be eafie tq conceivej how Motion may be 
dilated and fpreadj, or how parallel motions may become di- 
verging 5 yet I underftand not^ by what artifice any Limar 
motion can by a refracting fuperficies be infinitely dilated and 
rareiieds fo as to become super fiehli jOrj if that be fuppofed, 
yet I underftand as little, why it fliould be fpht at fo fmall an 
angle only, and not rather fpread and difperfed through the 
whole angle of Refraction. And further, though f can eafily 
imagiucp how Unlike motions may crofs one another $ yet I 
Cannot well conceive^how^they ftould coalefce into one umforrn 
n^otion, and then part again, and recover their former XJn- 
likenefs 5 notwithftanding that I conjecture the ways^by which 
ih6. Jnima^verlor m^y endeavour to explain it. So that the Di' 
rectj^form and undifturbed Pulfes fliould be fplit anddi*- 
fturbed by^efraetion | and yet the Oblique and difturbed 
Pulfes perfift without fplitting or further difturbance by fol^ 
lowing Refractions^ is (to me) as umntellFgible. And there is 
