not such an effect; and there are other
bodies, which to our other senses, seem not mov'd so much, which yet shine.
Thus Water and quick-silver, and most other liquors heated, shine not; and
several hard bodies, as Iron, Silver, Brass, Copper, Wood, &c. though very
often struck with a hammer, shine not presently, though they will all of
them grow exceeding hot; whereas rotten Wood, rotten Fish, Sea water,
Gloworms, &c. have nothing of tangible heat in them, and yet (where there
is no stronger light to affect the Sensory) they shine some of them so
Vividly, that one may make a shift to read by them.

It would be too long, I say, here to insert the discursive progress by
which I inquir'd after the proprieties of the motion of Light, and
therefore I shall only add the result.

And, First, I found it ought to be exceeding _quick_, such as those motions
of _fermentation_ and _putrefaction_, whereby, certainly, the parts are
exceeding nimbly and violently mov'd; and that, because we find those
motions are able more minutely to shatter and divide the body, then the
most violent heats _menstruums_ we yet know. And that fire is nothing else
but such a _dissolution_ of the Burning body, made by the most _universal
menstruum_ of all _sulphureous bodies_, namely, the Air, we shall in an
other place of this Tractate endeavour to make probable. And that, in all
extreamly hot shining bodies, there is a very quick motion that causes
Light, as well as a more robust that causes Heat, may be argued from the
celerity wherewith the bodyes are dissolv'd.

Next, it must be a _Vibrative motion_. And for this the newly mention'd
_Diamond_ affords us a good argument; since if the motion of the parts did
not return, the Diamond must after many rubbings decay and be wasted: but
we have no reason to suspect the latter, especially if we consider the
exceeding difficulty that is found in cutting or wearing away a Diamond.
And a Circular motion of the parts is much more improbable, since, if that
were granted, and they be suppos'd irregular and Angular parts, I see not
how the parts of the Diamond should hold so firmly together, or remain in
the same sensible dimensions, which yet they do. Next, if they be
_Globular_, and mov'd only with a _turbinated_ motion, I know not any cause
that can impress that motion upon the _pellucid medium_, which yet is done.
Thirdly, any other _irregular_ motion of the parts one amongst another,
must necessarily make t