are much of kin to those Spirits, &c. Others yet
require a _greater_, as _water_, and so others _much greater_, for almost
infinite degrees: For, I suppose there are very _few_ bodies in the world
that may not be made _aliquatenus_ fluid, by _some_ or _other_ degree of
agitation or heat.

Having therefore in short set down my Notion of a Fluid body, I come in the
next place to consider what _Congruity_ is; and this, as I said before,
being a _Relative property_ of a fluid, whereby it may be said to be _like_
or _unlike_ to this or that other body, whereby it _does_ or _does not mix_
with this or that body. We will again have recourse to our former
Experiment, though but a rude one; and here if we mix in the dish _several
kinds_ of sands, some of _bigger_, others of _less_ and finer bulks, we
shall find that by the agitation _the fine sand_ will _eject_ and _throw
out_ of it self all those _bigger_ bulks of small _stones_ and the like,
and those will _be gathered_ together all into _one_ place; and if there be
_other_ bodies in it of other natures, those also will be _separated_ into
a place by themselves, and _united_ or _tumbled_ up together. And though
this do not come up to the _highest property_ of _Congruity_, which is a
_Cohaesion_ of the parts of the fluid together, or a kind of _attraction_
and _tenacity_, yet this does as 'twere _shadow_ it out, and somewhat
resemble it; for just after the same manner, I suppose the _pulse_ of heat
to _agitate_ the small parcels of matter, and those that are of a _like
bigness_, and _figure_, and _matter_, will _hold_, or _dance_ together, and
those which are of a _differing_ kind will be _thrust_ or _shov'd_ out from
between them; for particles that are _similar_, will, like so many _equal
musical strings equally stretcht_, vibrate together in a kind of _Harmony_
or _unison_; whereas others that are _dissimilar_, upon what account
soever, unless the disproportion be otherwise counter-ballanc'd, will, like
so many _strings out of tune_ to those unisons, though they have the same
agitating _pulse_, yet make quite _differing_ kinds of _vibrations_ and
_repercussions_, so that though they may be both mov'd, yet are their
_vibrations_ so _different_, and so _untun'd_, as 'twere to each other,
that they _cross_ and _jar_ against each other, and consequently, _cannot
agree_ together, but _fly back_ from each other to their similar particles.
Now, to give you an instance how the _dispr