1. Of greater Moment in the Investigation of the Nature of Colours is the
Controversie, Whether those of the Rain-bow, and those that are often seen
in Clouds, before the Rising, or after the Setting of the Sun; and in a
word, Whether those other Colours, that are wont to be call'd Emphatical,
ought or ought not to be accounted True Colours. I need not tell you that
the Negative is the Common Opinion, especially in the Schools, as may
appear by that Vulgar distinction of Colours, whereby these under
Consideration are term'd Apparent, by way of Opposition to those that in
the other Member of the Distinction are call'd True or Genuine. This
question I say seems to me of Importance, upon this Account, that it being
commonly Granted, (or however, easie enough to be Prov'd) that Emphatical
Colours are Light it self Modify'd by Refractions chiefly, with a
concurrence sometimes of Reflections, and perhaps some other Accidents
depending on these two; if these Emphatical Colours be resolv'd to be
Genuine, it will seem consequent, that Colours, or at least divers of them,
are but Diversify'd Light, and not such Real and Inherent qualities as they
are commonly thought to be.
2. Now since we are wont to esteem the Echoes and other Sounds of Bodies,
to be True Sounds, all their Odours to be True Odours, and (to be short)
since we judge other Sensible Qualities to be True ones, because they are
the proper Objects of some or other of our Senses, I see not why Emphatical
Colours, being the proper and peculiar Objects of the Organ of Sight, and
capable to Affect it as Truly and as Powerfully as other Colours, should be
reputed but Imaginary ones.
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
other Passages which you'l meet with in this Tract, if I take this Occasion
to observe to you, that if Water be Agitated into Froth, it exhibits you
know a White colour, which soon after it Loses upon the Resolution of the
Bubbles into Air and Water, now in this case either the Whiteness of the
Froth is a True Colour or not, if it be, then True Colours, supposing the
Water pure and free from Mixtures of any thing Tenacious, may be as
Short-liv'd as those of the Rain-bow; also the Matter, wherein the
Whiteness did Reside, may in a few moments perfectly Lose all foot-steps or
remains of it. And besides, even Diaphanous Bodies may be capable of
exhibiting True Colours by Reflection, for that Whiteness is so produc'd,
we shall anon make it probable. But if on the other side it be said, that
the Whiteness of Froth is an Emphatical Colour, then it must no longer be
said, that Fantastical Colours require a certain Position of the Luminary
and the Eye, and must be Vary'd or Destroy'd by the Change thereof, since
Froth appears White, whether the Sun be Rising or Setting, or in the
Meridian, or any where between it and the Horizon, and from what
(Neighbouring) place soever the Beholders Eye looks upon it. And since by
making a Liquor Tenacious enough, yet without Destroying its Transparency,
or Staining it with any Colour, you may give the Little Films, whereof the
Bubbles consist, such a Texture, as may make the Froth last very many
Hours, if not some Days, or even Weeks, it will render it somewhat Improper
to assign Duration for the Distinguishing Character to Discriminate Genuine
from Fantastical Colours. For such Froth may much outlast the Undoubtedly
true Colours of some of Nature's Productions, as in that Gaudy Plant not
undeservedly call'd the Mervail of _Peru_, the Flowers do often Fade, the
same Day they are Blown; And I have often seen a _Virginian_ Flower, which
usually Withers within the compass of a Day; and I am credibly Inform'd,
that not far from hence a curious Herborist has a Plant, whose Flowers
perish in about an Hour. But if the Whiteness of Water turn'd into Froth
must therefore be reputed Emphatical, because it appears not that the
Nature of the Body is Alter'd, but only that the Disposition of its Parts
in reference to the Incident Light is Chang'd, why may not the Whiteness be
accounted Emphatical too, which I shall shew anon to be Producible, barely
by such another change in Black Horn? and yet this so easily acquir'd
Whiteness seems to be as truly its Colour as the Blackness was before, and
at least is more Permanent than the Greenness of Leaves, the Redness of
Roses, and, in short, than the Genuine Colours of the most part of Nature's
Productions. It may indeed be further Objected, that according as the Sun
or other Luminous Body changes place, these Emphatical Colours alter or
vanish. But not to repeat what I have just now said, I shall add, that if a
piece of Cloath in a Drapers Shop (in such the Light being seldome Primary)
be variously Folded, it will appear of differing Colours, as the Parts
happen to be more Illuminated or more Shaded, and if you stretch it Flat,
it will commonly exhibit some one Uniform Colour, and yet these are not
wont to be reputed Emphatical, so that the Difference seems to be chiefly
this, that in the Case of the Rain-bow, and the like, the Position of the
Luminary Varies the Colour, and in the Cloath I have been mentioning, the
Position of the Object does it. Nor am I forward to allow that in all Cases
the Apparition of Emphatical Colours requires a Determinate position of the
Eye, for if Men will have the Whiteness of Froth Emphatical, you know what
we have already Inferr'd from thence. Besides, the Sun-beams trajected
through a Triangular Glass, after the manner lately mention'd, will, upon
the Body that Terminates them, Paint a Rain-bow, that may be seen whether
the Eye be plac'd on the Right Hand of it or the Left, or Above or Beneath
it, or Before or Behind it; and though there may appear some Little
Variation in the Colours of the Rain-bow, beheld from Differing parts of
the Room, yet such a Diversity may be also observ'd by an Attentive Eye in
Real Colours, look'd upon under the like Circumstances, Nor will it follow,
that because there remains no Footsteps of the Colour upon the Object, when
the Prism is Remov'd, that therefore the Colour was not Real, since the
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
confessedly Genuine may. But when all this is said, _Pyrophilus_, I must
Advertise you, that it is but Problematically Spoken, and that though I
think the Opinion I have endeavour'd to fortifie Probable, yet a great part
of our Discourse concerning Colours may be True, whether that Opinion be so
or not.
* * * * *