differ in their disposition to exhibit this or that particular Colour. Colours are not Qualifications of Light, derived from Refractions, or Reflections of natural Bodies, (as 'tis generally believed) but Original and connate Properties, which in divers Rays are divers. Some Rays are disposed to exhibit a red Colour and no other; some a yellow and no other, some a green and no other, and so of the rest. Nor are there only Rays proper and particular to the more eminent Colours, but even to all their intermediate Gradations.
- To the same degree of Refrangibility ever belongs the same Colour, and to the same Colour ever belongs the same degree of Refrangibility. The least Refrangible Rays are all disposed to exhibit a Red Colour, and contrarily those Rays, which are disposed to exhibit a Red Colour, are all the least Refrangible: So the most Refrangible Rays are all disposed to exhibit a deep Violet Colour, and contrarily those which are apt to exhibit such a Violet Colour,