The importance of the Question, you propose, would oblige me to refer you to the Dialogue about a good Hypothesis, and some other Papers of that kind, where you may find my thoughts about the advantages of the Mechanical Hypothesis somewhat amply set down, and discours’d of. But, since your desires confine me to deliver in few words, not what I believe resolvedly, but what I think may be probably said for the Preference or the Preeminence of the Corpuscular Philosophy above Aristotles, or that of the Chymists, you must be content to receive from me, without any Preamble, or exact Method, or ample Discourses, or any other thing that may cost many words, a succinct mention of some of the chief Advantages of the Hypothesis we incline to. And I the rather comply, on this occasion, with your Curiosity, because I have often observ’d you to be allarm’d and disquieted, when you hear of any Book that pretends to uphold, or repair the decaying Philosophy of the Schools, or some bold Chymist, that arrogates to those of his Sect the Title of Philosophers, and pretends to build wholly upon Experience, to which he would have all other Naturalists thought strangers. That therefore you may not be so tempted to despond, by the Confidence or Reputation of those Writers, that do some of them applaud, and others censure, what, I fear, they do not understand, (as when the Peripateticks cry up, Substantial Forms, and the Chymists, Mechanical Explications) of Nature’s Phaenomena, I will propose some Considerations, that, I hope, will not onely keep you kind to the Philosophy you have embrac’d, but perhaps, (by some Considerations which you have not yet met with,) make you think it probable, that the new Attempts you hear of from time to time, will not overthrow the Corpuscularian Philosophy, but either be foiled by it, or found reconcilable to it.
But when I speak of the Corpuscular or Mechanical Philosophy, I am far from meaning with the Epicureans, that Atoms, meeting together by chance in an infinite Vacuum, are able of themselves to produce the World, and all its Phaenomena; nor with some Modern Philosophers, that, supposing God to have put into the whole Mass of Matter such an invariable quantity of Motion, he needed do no more to make the World, the material parts being able by their own unguided Motions, to cast themselves into such a System (as we call by that name); But I plead onely for such a Philosophy, as reaches but to things purely Corporeal, and distinguishing between the first original of things, and the subsequent course of Nature, teaches, concerning the former, not onely that God gave Motion to Matter, but that in the beginning He so guided the various Motions of the parts of it, as to contrive them into the World he design’d they should compose, (furnish’d with the Seminal Principles and Structures or Models of Living Creatures,) and establish’d those Rules of Motion, and that order amongst things Corporeal, which we are wont to call the Laws of Nature. And having told this as to the former, it may be allowed as to the latter to teach, That the Universe being once fram’d by God, and the Laws of Motion being setled and all upheld by His incessant concourse and general Providence; the Phaenomena of the World thus constituted, are Physically produc’d by the Mechanical affections of the parts of Matter, and what they operate upon one another according to Mechanical Laws. And now having shewn what kind of Corpuscular Philosophy ‘tis that I speak of I proceed to the particulars that I thought the most proper to recommend it.
I. The first thing that I shall mention to this purpose, is the Intelligibleness or Clearness of Mechanical Principles and Explications. I need not tell you, that among the Peripateticks, the Disputes are many and intricate about Matter, Privation, Substantial Forms, and their Eduction, &c. And the Chymists are sufficiently puzled, (as I have elsewhere shewn,) to give such definitions and accounts of their Hypostatical Principles, as are reconcileable to one another, and even to some obvious Phaenomena. And much more dark and intricate are their Doctrines about the Archeus, Astral Beings, Gas, Blass, and other odd Notions, which perhaps have in part occasion’d the darkness and ambiguity of their expressions, that could not be very clear, when their Conceptions were far from being so. And if the Principles of the Aristotelians and Spagyrists are thus obscure, ‘tis not to be expected, the Explications that are made by the help onely of such Principles should be clear. And indeed many of them are either so general and slight, or otherwise so unsatisfactory, that granting their Principles, ‘tis very hard to understand or admit their applications of them to particular Phaenomena. And even in some of the more ingenious and subtle of the Peripatetick Discourses upon their superficial and narrow Theories, me thinks, the Authors have better plaid the part of Painters than Philosophers, and have onely had the skill, like Drawers of Landskips, to make men fancy, they see Castles and Towns, and other Structures that appear solid and magnificent, and to reach to a large extent, when the whole Piece is superficial, and made up of Colours and Art, and compris’d within a Frame perhaps scarce a yard long. But to come now to the Corpuscular Philosophy, men do so easily understand one anothers meaning, when they talk of Local Motion, Rest, Bigness, Shape, Order, Situation, and Contexture of Material Substances; and these Principles do afford such clear accounts of those things, that are rightly deduc’d from them onely, that even those Peripateticks or Chymists, that maintain other Principles, acquiesce in the Explications made by these, when they can be had, and seek not any further, though perhaps the effect be so admirable, as would make it pass for that of a hidden Form, or Occult Quality. Those very Aristotelians, that believe the Celestial Bodies to be mov’d by Intelligences, have no recourse to any peculiar agency of theirs to account for Eclipses. And we laugh at those East-Indians, that, to this day, go out in multitudes, with some Instruments that may relieve the distressed Luminary, whose loss of Light they fancy to proceed from some fainting fit, out of which it must be rouz’d. For no Intelligent man, whether Chymist or Peripatetic, flies to his peculiar Principles, after he is informed, that the Moon is Eclipsed by the interposition of the Earth betwixt her and it, and the Sun by that of the Moon betwixt him and the Earth. And when we see the Image of a Man cast into the Air by a Concave Spherical Looking-glass, though most men are amaz’d at it, and some suspect it to be no less than an effect of Witchcraft, yet he that is skill’d enough in Catoptricks, will, without consulting Aristotle, or Paracelsus, or flying to Hypostatical Principles and Substantial Forms, be satisfied, that the Phaenomenon is produc’d by the beams of Light reflected, and thereby made convergent according to Optical, and consequently Mathematical Laws.