particle of air, as well as other bodies, yet it cannot make bonds for itfelf, and hold together the parts that make up every the leaft corpufcle of that materia fubtilis. So that that hypothefis, how ingeniously foever explained, by fhowing that the parts of fenfible bodies are held together by the preffure of other external infenfible bodies, reaches not the parts of the ether itself: And by how much the more evident it proves, that the parts of other bodies are held together by the external preffure of the ether, and can have no other conceivable cause of their cohesion and union, by fo much the more it leaves us in the dark concerning the cohefion of the parts of the corpufcles of the ether itself; which we can neither conceive without parts, they being bodies, and divifible; nor yet how their parts cohere, they wanting that cause of cohesion which is given of the cohesion of all other bodies.

§ 24.

BUT in truth, the preffure of any ambient fluid, how great foever, can be no intelligible caufe of the cohefion of the fold parts of matter. For though fuch a preffure may hinder the avulfion of two polished fuperficies one from another, in a line perpendicular to them, as in the experiment of two polifhed marbles; yet it can never, in the least, hinder the feparation by a motion, in a line parallel to those furfaces; because the ambient fluid, having a full liberty to fucceed in each point of space, deferted by a lateral motion, refifts fuch a motion of bodies fo joined, no more than it would refift the motion of that body, were it on all fides environed by that fluid, and touched no other body: And therefore, if there were no other caufe of cohefion, all parts of bodies muft he eafily feparable by fuch a lateral fliding motion: For if the preffure of the ether be the adequate caufe of cohesion, wherever that caufe operates not, there can be no cohefios. And fince it cannot operate against fuch a lateral feparation (as has been fhown), therefore, in every imaginary plain, interfecting any mals of matter, there could be no more cohesion, than of two polifhed furfaces, which will always, not

withstanding any imaginable preffure of a fluid, eafily flide one from another. So that perhaps, how clear an idea foever we think we have of the extenfion of body, which is nothing but the cohesion of folid parts, he that fhall well confider it in his mind, may have reason to conclude, that it is as eafy for him to have a clear idea, how the foul thinks, as how body is extended. For fince body is no farther, nor otherwife extended, than by the union and cohefion of its folid parts, we fhall very ill comprehend the extenfion of body, without understanding wherein confifts the union and cohefion of its parts; which feems to me as incomprehenfible, as the manner of thinking, and how it is performed.

25.

I ALLOW it is usual for most people to wonder, how any one should find a difficulty in what they think they every day obferve. Do we not fee (will they be ready to fay) the parts of bodies ftick firmly together? Is there any thing more common? And what doubt can there be made of it? And the like I fay concerning thinking and voluntary motion. Do we not every moment experiment it in ourfelves; and therefore can it be doubted? The matter of fact is clear, I confefs; but when we would a little nearer look into it, and confider how it is done, there I think we are at a lofs, both in the one and the other; and can as little understand how the parts of body cohere, as how we ourselves perceive, or move. I would have any one intelligibly explain to me, how the parts of gold, or brafs (that but now in fufion were as loose from one another, as the particles of water, or the fands of an hour-glass), come in a few moments to be fo united, and adhere fo ftrongly one to another, that the utmost force of mens arms cannot feparate them: A confidering man will, I fuppofe, be here at a lofs to fatisfy his own or another man's understanding.

§ 26.

THE little bodies that compofe that fluid we call water, are fo extremely fmall, that I have never heard of any one, who, by a microscope, (and yet I have heard of fome that have magnified to 10,000, nay, to much above VOL. II.

B

100,000 times) pretended to perceive their diftinct bulk, figure or motion: And the particles of water are alfo fo perfectly loofe one from another, that the least force fenfibly separates them. Nay, if we confider their perpetual motion, we must allow them to have no cohesion one with another; and yet, let but a fharp cold come, and they unite, they confolidate, thefe little atoms cohere, and are not, without great force, feparable. He that could find the bonds that tie thefe heaps of loose little bodies together fo firmly; he that could make known the cement that makes them stick fo faft one to another, would difcover a great, and yet unknown fecret; and yet when that was done, would he be far enough from making the extenfion of body (which is the cohefion of its folid parts) intelligible, till he could fhow wherein confifted the union, or confolidation of the parts of those bonds, or of that cement, or of the leaft particle of matter that exifts. Whereby it appears, that this primary and fuppofed obvious quality of body, will be found, when examined, to be as incomprehenfible as any thing belonging to our minds, and a folid extended fubftance as hard to be conceived as a thinking immaterial one, whatever difficulties fome would raife against it.

$27.

FOR, to extend our thoughts a little farther, that preffure which is brought to explain the cohesion of bodies, is as unintelligible as the cohesion itself. For if matter be confidered, as no doubt it is, finite, let any one fend his contemplation to the extremities of the universe, and there fee what conceivable hoops, what bond he can imagine to hold this mafs of matter in so close a preffure together; from whence fteel has its firmness, and the parts of a diamond their hardness and indiffolubility. If matter be finite, it must have its extremes; and there must be fomething to hinder it from fcattering afunder. If, to avoid this difficulty, any one will throw himself into the fuppofition and abyfs of infinite matter, let him confider what light he thereby brings to the cohefion of body, and whether he be ever the nearer making it intelligible, by refolving it into a fuppofition, the moft abfurd and moft incomprehenfible of all other:

So far is our extenfion of body (which is nothing but the cohesion of folid parts) from being clearer, or more distinct, when we would inquire into the nature, cause, er manner of it, than the idea of thinking.

§ 28. Communication of Motion, by Impulse or by Thought, equally intelligible.

ANOTHER idea we have of body, is the power of communication of motion by impulfe; and of our fouls, the power of exciting motion by thought. These ideas, the bne of body, the other of our minds, every day's experience clearly furnishes us with; but if, here again, we inquire how this is done, we are equally in the dark. For in the communication of motion by impulfe, wherein as much motion is loft to one body as is got to the other, which is the ordinarieft cafe, we can have no other conception, but of the paffing of motion out of one body into another; which, I think, is as obfcure and inconceivable, as how our minds move or ftop our bodies by thought, which we every moment find they do. The increase of motion by impulfe, which is obferved or believed fometimes to happen, is yet harder to be understood. We have, by daily experience, clear evidence of motion produced both by impulfe and by thought; but the manner how, hardly comes within ur comprehenfion; we are equally at a lofs in both. So that, however we confider motion and its communication either from body or fpirit, the idea which belongs to fpirit is at least as clear as that which belongs to body. And if we confider the active power of moving, or, as I may call it, motivity, it is much clearer in fpirit than body; fince two bodies, placed by one another at reft, will never afford us the idea of a power in the one to move the other, but by a borrowed motion: Whereas the mind, every day, affords us ideas of an active power of moving of bodies; and therefore it is worth our confideration, whether active power be not the proper attribute of fpirits, and paffive power of matter. Hence may be conjectured, that created spirits are not totally feparate from matter, because they are both active and paffive. Pure fpirit, viz. God, is

only active; pure matter is only paffive; thofe beings that are both active and paffive, we may judge to partake of both. But be that as it will, I think we have as many, and as clear ideas belonging to spirit, as we have belonging to body, the fubftance of each being equally unknown to us; and the idea of thinking in fpirit, as clear as of extenfion in body; and the communication of motion by thought, which we attribute to fpirit, is as evident as that by impulfe, which we afcribe to body. Conftant experience makes us fenfible of both of thefe, though our narrow understandings can com→ prehend neither. For when the mind would look beyond those original ideas we have from fenfation or reflection, and penetrate into their caufes and manner of production, we find still it discovers nothing but its own fhort-fightedness.

§ 29.

To conclude, fenfation convinces us, that there are solid extended fubftances; and reflection, that there are thinking ones: experience affures us of the exiftence of fuch beings; and that the one hath a power to move body by impulfe, the other by thought; this we cannot doubt of. Experience, I fay, every moment furnishes us with the clear ideas, both of the one and the other; but beyond thefe ideas as received from their proper fources, our faculties will not reach. If we would inquire farther into their nature, caufes, and manner, we perceive not the nature of extenfion clearer than we do of thinking. If we would explain them any farther, one is as cafy as the other; and there is no more difficulty to conceive how a substance we know not, should by thought, fet body into motion, than how a fubftance we know not, fhould by impulfe, fet body into motion; fo that we are no more able to discover wherein the ideas belonging to body confift, than those belonging to fpirit. From whence it feems probable to me, that the fimple ideas we receive from fenfation and reflection, are the boundaries of our thoughts, beyond which the mind, whatever efforts it would make, is not able to advance one jot; nor can it make any discoveries, when it would pry into the nature and hidden causes of thofe ideas.