they have done of Colours. And your _Sennertus_ Himself (though an
Author I much value) would I fear have been exceedingly puzl'd to
resolve, by the _Tria Prima_, halfe that Catalogue of Problems, which
he challenges the Vulgar Peripateticks to explicate by their four
Elements.[26] And supposing it were true, that Salt or Sulphur were
the Principle to which this or that Quality may be peculiarly
referr'd, yet though he that teaches us this teaches us something
concerning That quality, yet he Teaches us but something. For indeed
he does not Teach us That which can in any Tollerable measure satisfie
an inquisitive Searcher after Truth. For what is it to me to know,
that such a quality resides in such a Principle or Element, whilst I
remain altogether ignorant of the Cause of that quality, and the
manner of its production and Operation? How little do I know more then
any Ordinary Man of Gravity, if I know but that the Heaviness of mixt
bodies proceeds from that of the Earth they are compos'd of, if I know
not the reason why the Earth is Heavy? And how little does the Chymist
teach the Philosopher of the Nature of Purgatition, if he only tells
him that the Purgative Vertue of Medicines resides in their Salt? For,
besides that this must not be conceded without Limitation, since the
purging parts of many Vegetables Extracted by the Water wherein they
are infus'd, are at most but such compounded Salts, (I mean mingl'd
with Oyle, and Spirit, and Earth, as Tartar and divers other Subjects
of the Vegetable Kingdom afford;) And since too that Quicksilver
precipitated either with Gold, or without Addition, into a powder, is
wont to be strongly enough Cathartical, though the Chymists have not
yet prov'd, that either Gold or Mercury have any Salt at all, much
less any that is Purgative; Besides this, I say, how little is it to
me, to know That 'tis the Salt of the Rhubarb (for Instance) that
purges, if I find That it does not purge as Salt; since scarce any
Elementary Salt is in small quantity cathartical. And if I know not
how Purgation in general is effected in a Humane Body? In a word, as
'tis one thing to know a mans Lodging, and another, to be acquainted
with him; so it may be one thing to know the subject wherein a Quality
principally resides, and another thing to have a right notion and
knowledg of the quality its self. Now that which I take to be the
reason of this Chymical Deficiency, is the same upon whose account I
think the _Aristotelian_ and divers other Theories incompetent to
explicate the Origen [Errata: origine] of Qualities. For I am apt to
think, that men will never be able to explain the _Phaenomena_ of
Nature, while they endeavour to deduce them only from the Presence and
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