Light was truly Modify'd by the Refraction and Reflection it Suffer'd in
its Trajection through the Prism; and the Object in our case serv'd for a
Specular Body, to Reflect that Colour to the Eye. And that you may not be
Startled, _Pyrophilus_, that I should Venture to say, that a Rough and
Coiour'd Object may serve for a _Speculum_ to Reflect the Artificial
Rain-bow I have been mentioning, consider what usually happens in Darkned
Rooms, where a Wall, or other Body conveniently Situated within, may so
Reflect the Colours of Bodies, without the Room, that they may very clearly
be Discern'd and Distinguish'd, and yet 'tis taken for granted, that the
Colours seen in a Darkned Room, though they leave no Traces of themselves
upon the Wall or Body that Receives them, are the True Colours of the
External Objects, together with which the Colours of the Images are Mov'd
or do Rest. And the Errour is not in the Eye, whose Office is only to
perceive the Appearances of things, and which does Truly so, but in the
Judging or Estimative faculty, which Mistakingly concludes that Colour to
belong to the Wall, which does indeed belong to the Object, because the
Wall is that from whence the Beams of Light that carry the Visible
_Species_, do come in Straight Lines directly to the Eye, as for the same
Reason we are wont at a certain Distance from Concave Sphærical Glasses, to
perswade our Selves that we see the Image come forth to Meet us, and Hang
in the Air betwixt the Glass and Us, because the Reflected Beams that
Compose the image cross in that place, where the Image seems to be, and
thence, and not from the Glass, do in Direct Lines take their Course to the
Eye, and upon the like Cause it is, that divers Deceptions in Sounds and
other Sensible Objects do depend, as we elsewhere declare.

5. I know not, whether I need add, that I have purposely Try'd, (as you'l
find some Pages hence, and will perhaps think somewhat strange) that
Colours that are call'd Emphatical, because not Inherent in, the Bodies in
which they Appear, may be Compounded with one another, as those that are