And if we have (which perchance you'l allow) formerly evinc'd Colour, (when
the word is taken in its more Proper sense) to be but Modify'd Light, there
will be small Reason to deny these to be true Colours, which more
manifestly than others disclose themselves to be produc'd by
Diversifications of the Light.

3. There is indeed taken notice of a Difference betwixt these Apparent
colours, and those that are wont to be esteem'd Genuine, as to the
Duration, which has induc'd some Learned Men to call the former rather
Evanid than Fantastical. But as the Ingenious _Gassendus_ does somewhere
Judiciously observe, if this way of Arguing were Good, the Greeness of a
Leaf ought to pass for Apparent, because, soon Fading into a Yellow, it
Scarce lasts at all, in comparison of the Greeness of an Emerauld. I shall
add, that if the Sun-beams be in a convenient manner trajected through a
Glass-prism, and thrown upon some well-shaded Object within a Room, the
Rain-bow thereby Painted on the Surface of the Body that Terminates the
Beams, may oftentimes last longer than Some Colours I have produc'd in
certain Bodies, which would justly, and without scruple be accounted
Genuine Colours, and yet suddenly Degenerate, and lose their Nature.

4. A greater Disparity betwixt Emphatical Colours, and others, may perhaps
be taken from this, that Genuine Colours seem to be produc'd in Opacous
Bodies by Reflection, but Apparent ones in Diaphanous Bodies, and
principally by Refraction, I say Principally rather than Solely, because in
some cases Reflection also may concurr, but still this seems not to
conclude these Latter Colours not to be True ones. Nor must what has been
newly said of the Differences of True and Apparent Colours, be interpreted
in too Unlimited a Sense, and therefore it may perhaps somewhat Assist you,
both to Reflect upon the two fore-going Objections, and to judge of some