The Praeface.

THe Origine (Pyrophilus) and Nature of the Qualities of Bo∣dies, is a Subject, that I have long lookt upon, as one of the most Im∣portant and Usefull that the Naturalist can pitch upon for his Contemplation. For the Knowledge we have of the Bodies without Us, being for the Most part fetched from the In∣formations the Mind receives by the Senses, we scarce know any thing else in Bodies, upon whose account they can worke upon our Senses save their Qualities: For as to the Substantial Formes, which some Imagine to be in all Na∣turall Bodies, it is not halfe so Evident, that there are such, as it is, that the wisest of those that do admit them, Confesse, that they do not well Know them.* And as tis by their Qua∣lities, that Bodies act Immediately upon our Page  [unnumbered] Senses, so 'tis by vertue of those Attributes likewise, that they act upon Other bodies, & by that action produce in Them, & oftentimes in Themselves those Changes, that sometimes we call Alterations, and sometimes Genera∣tion, or Corruption.

And 'tis chiefly by the Knowledge, such as it is, that Experience, (not Art) hath taught Us, of these differing Qua∣lities of Bodies, that we are enabled, by a due application of Agents to Patients, to exer∣cise the little Empire, that we have either Ac∣quir'd or Regain'd over the Creatures. But I think not the contemplation of Qualities more Noble & Useful, then I find it Difficult; For what is wont to be taught us of Qualities in the Schools, is so Slight and ill grounded, that it may be doubted, whether they have not rather Obscured, then Illustrated the things they should have explain'd. And I was quickly discouraged from expecting to learne much from them, of the Nature • divers Particular Qualities, when I found that except some few, which they tell You i•Page  [unnumbered] General may be deduced, (by wayes they leave those to guesse at that can,) from those foure Qualities, they are pleas'd to call the First; they confesse, that the rest spring from those Forms of Bodies, whose particular Natures, the judiciousest of them acknowledge, they cannot comprehend. And Aristotle him∣self not only doth (as we shall see anon) give us of Qualitie in Generall, (which yet seems far more easily defineable, then many a Particular Quality,) no other then such a definition, as is as Obscure, as the thing to be declared by it; but I Observe not without some wonder, that in his eight Books of Physicks, where he professedly treats of the Generall Affections of Naturall things, he leaves out the Doctrine of Qualities; as after him Magirus, and divers other Wri∣ters of the Peripatetick Physiologie have done: which (by the way) I cannot but look upon as an Omission, since Qualities doe as well seem to belong to Naturall Bodies Generally consider'd, as Place, Time, Moti∣on, and those other things, which upon that Page  [unnumbered] account are wont to be Treated of in the Generall part of Natural Philosophy. The most Ingenious Des Cartes has something concerning some Qualities; but though for Reasons elsewhere express•d, I have pur∣posely Forborn to peruse his Systeme of Philo∣sophy; yet I find by Turning over the Leaves that he has Left most of the other Qualities Ʋntreated of, & of Those, that are more pro∣perly call'd Sensible, he Speaks but very Briefly & Generally; rather considering what they do upon the Organs of Sense, then what Changes happen in the Objects themselves, to make them Cause in us a Perception sometimes of one Quality, and sometimes of Another. Besides, that his Explications, do many of them so depend upon His pecu∣liar Notions, (of a Materia Subtilis, Glo∣buli Secundi Elementi, and the like) and These as it became so Great a Person, he has so Interwoven with the rest of his Hypothe∣sis, that They can seldome be made Ʋse of without Adopting his whole Philosophy Epicurus indeed, and his Scholiast Lucre∣tius,Page  [unnumbered] have Given some good Hints concer∣ning the Nature of some few Qualities. But beside, that even these Explications are divers of them either Doubtfull or Im∣perfect, or both, there are many other Qua∣lities, which are left for Others to Treat of. And this is the Second and Maine Difficul∣ty, which I find in investigating the Na∣ture of Qualities, Namely, that Whatever be to be thought of the Generall Theoryes of Aristotle, or other Philosophers, concer∣ning Qualities; we evidently Want That, upon which a Theory, to be Solid and Ʋsefull, must be Built; I mean an Experimentall History of them. And this we so Want, that except perhaps what Mathematicians have done concerning Sounds, and the Observations (rather then Experiments) that our Illustrious Verulam hath (in some few Pages) say'd of Heat, in his short Essay, De Formâ Calidi; I know not Any one Quality, of which any Author has yet Given us an any thing competent History. These things I mention to You, Pyrophilus, not Page  [unnumbered] at all to derogate from those Great Men; whose design seems rather to have been to deliver Principles and Summaries of Phi∣losophy, then to insist upon Particulars; but for this purpose, that since the Nature of Qualities is so beneficiall a speculation, my labours may not be look'd upon as wholly Uselesse, though I can contribute but a little to the clearing of it: and that since 'tis so abstruse a subject, I may be pardon'd, if I sometimes misse the marke, and leave diverse things uncompleated; That being but what such great Philosophers have done be∣fore mee.

But, Pyrophylus, before I proceed to give You my Notes upon this part of our Author's Essay, that you may rightly understand my Intention in them, it will be requisite to give you three or foure Advertisements.

And first, when ever I shall speake in∣definitely of Substantiall forms, I would al∣wayes be understood to except the Reasonable Soule, that is said to inform the humane Bo∣dy; which Declaration I here desire may be Page  [unnumbered] taken notice of, once for all.

Secondly, Nor am I willing to treat of the Origine of Qualities in beasts; partly be∣cause I would not be engaged to examine, of what Nature their Soules are, and partly be∣cause it is difficult in most cases, (at least for one, that is compassionate enough,) either to make experiments upon Living a∣nimals, or to judg what influence their Life may have, upon the change of Qualities, pro∣duc'd by such Experiments.

Thirdly, The occasion of the following Reflections, being onely this; that our Author in that part of his Essay concerning Salt∣peter, whereto these Notes referre, does briefly Intimate some Notions about the Nature and Origine of Qualities; You must not exspect, that I, whose Method leads me but to Write some Notes upon this, and some other parts of this Essay, should make Solemne or Elaborate discour∣ses concerning the Nature of particular Qualities, and that I should fully deliver my own apprehensions concerning those Page  [unnumbered] Subjects. For as I elsewhere sufficiently Intimate, that in these first Notes I Write as a Corpuscularian, & set down those Things onely, that seem to have a tendency to Illu∣strate or Countenance the Notions or Fan∣cies imply'd in our Author's Essay: So I must here Tell you, that I neither have now the Leasure, nor Pretend to the Skill, to deli∣ver Fully the History or to Explicate Parti∣cularly the Nature of Each several Quality.

Fourthly, But I consider, that the Schools have of late much Amus'd the World, with a way they have got, of Referring all Natu∣rall Effects to certain Entities, that they call Reall Qualities, and accordingly Attri∣bute to them a Nature distinct from the Mo∣dification of the Matter they belong to, & in some cases Separable from all Matter what∣soever, by which Meanes they have, as farre forth as their Doctrine is Acquiesc'd in, made it thought Needlesse or Hopeless for men to Employ their Industry, in searching into the Nature of Particular Qualities, & their Effects. As if, (for Instance) it be De∣manded, Page  [unnumbered] how Snow comes to dazle the Eyes, they will answer, that 'tis by a Quality of Whiteness that is in It; which makes all very white Bodies produce the same Effect; And if You, ask what this Whiteness is, They will tell you no more in substance, then that tis a reall Entity, which denominates the Parcel of Matter, to which it is Joyn'd, White; & if You further Enquire, what this real Entity, which They call a Quality, is, You will find, as Wee shall see anon, that They either Speak of it much after the same rate, that They do of their Substantiall Forms; (as indeed some of the Modern'st teach, That a Quality af∣fects the Matter it belongs to, per modum formae secundariae, as they speak) or at least they will not Explicate it more Intelligibly.

And accordingly if you further Ask them, how white Bodies in Generall do rather Produce this effect of dazling the Eyes, then Green or Blew ones, instead of being told, that the former sort of Bodies reflect Outwards, and so to the Eye farre more of the Incident Light, then the Latter; You shall perchance Page  [unnumbered] be told, that 'tis their respective Natures so to act, by which way of dispatching difficulties, they make it very easy to solve All the Phoenomena of Nature in Generall, but make men think it impossible to ex∣plicate almost Any of them in Particular.

And though the Unsatisfactorisness and Barrennesse of the School. Philosophy have perswaded a great many Learned Men, especially Physicians, to substitute the Chy∣mists Three principles, instead of those of the Schools; and though I have a very good opinion of Chymistry it self, as 'tis a Practical Art; yet as 'tis by Chymists pretended to containe a Systeme of Theori∣call Principles of Philosophy, I fear it will afford but very little satisfaction to a se∣vere enquirer, into the Nature of Quali∣ties. For besides that, as we shall more par∣ticularly see anon, there are Many Quali∣ties, which cannot with any probability be deduc'd from Any of the three Princi∣ples; those that are ascrib'd to One, or other of them, cannot Intelligibly be explica∣ted, Page  [unnumbered] without recourse to the more Compre∣hensive Principles of the Corpuscularian Philosophy. To tell us, for instance, that all Solidity proceeds from Salt, onely in∣forming us, (where it can plausibly be pre∣tended) in what materiall principle or ingredient that Quality resides, not how it is produced; for this doth not teach us, (for example) how Water even in exact∣ly clos'd vessels comes to be frozen into Ice; that is, turn'd from a fluid to a Solid Body, without the accession of a saline ingredi∣ent (which I have not yet found pretended, especially Glasse being held Impervious to Salts.) Wherefore, Pyrophilus, I thought it might much conduce to the understan∣ding the Nature of Qualities, To shew how they are Generated; and by the same way, I hop'd it might remove in some measure the obstacle, that these Dark and Narrow Theo∣ries of the Peripateticks and Chymists may prove to the Advancement of solid and use∣full Philosophy. That then, which I chie∣fly aime at, is to make it Probable to you by Page  [unnumbered] Experiments, (which I Think hath not yet beene done:) That allmost all sorts of Qualities, most of which have been by the Schooles either left Unexplicated, or Ge∣nerally referr'd, to I know not what In∣comprehensible Substantiall Formes; may be produced Mechanically, I mean by such Corporeall Agents, as do not appear, either to Work otherwise, then by vertue of the Motion, Size, Figure, and Contrivance of their own Parts, (which Attributes I call the Mechanicall Affections of Mat∣ter, because to Them men willingly Referre the various Operations of Mechanical En∣gines:) or to Produce the new Qualities exhibited by those Bodies their Action changes, by any other way, then by chan∣ging the Texture, or Motion, or some other Mechanical Affection of the Body wrought upon. And this if I can in any Passable mea∣sure do, though but in a generall way, in some or other of each of these Three Sorts, into which the Peripateticks are wont to Divide the Qualities of Bodies, I hope I shall have Page  [unnumbered] done no uselesse Piece of Service to Natural Philosophy, Partly by exciting You, and Your Learned Friends, to Enquire after more Intelligible and Satisfactory wayes of explicating Qualities, and Partly by Be∣ginning such a Collection of Materials to∣wards the History of those Qualities, that I shall the most largely Insist on, as Heat, Co∣lours, Fluidity and Firmnesse, as may invite You, and other Ingenious •en, to contribute also their Experiments, and Observations to so Usefull a VVork, and thereby lay a foun∣dation, whereon You, and perhaps I, may su∣perstruct a more Distinct and Explicite Theory of Qualities, then I shall at present adventure at. And though I Know, that some of the things my Experiments tend to Manifest, may likewise be Confirm'd by the more obvious Phaenomena of Nature, yet I Praesume You will not dislike my Cho∣sing to entertaine You with the Former, (though without at all Despising, or so much as strictly forbearing to Employ the Latter,) because the Changes of Qualities made by Page  [unnumbered] Our Experiments will for the most part be more Quick & Conspicuous, and the agents made use of to produce them, being of our own Applying, and oftentimes of our own Praeparation, we may be thereby assisted the better to judge of what they Are, and to make an aestimate of what 'tis they Do.