paragraph becomes plain alfo from confidering that refiftance is the fame with re-action; for fince action and re-action are equal, the re-action of matter may ftill be greater and greater, as the action upon it is and greater.

greater

XIII. But contrarily, if we confider the fame quantity of matter or body A, absolutely, and without any respect to a fixt state, the refiftance of it is immutable, and always as much the fame, as the folidity or extenfion of it: fo that it is impoffible that any force impreffed upon it ab extra, fhould take it ultimately off, or leffen it, or encrease it; or, .in a word, make it other than it always was, before fuch force was impreffed. It is true, the resistance it makes to a change of its present state may be overcome; but then it makes just as much resistance to perfevere in that new ftate, as in the former: and that refistance again may be overcome, and a new ftate of motion or reft induced upon it; yet it will as obftinately continue in that state, as in any of the other two. And fo on endlefly. If any force ab extra overcomes the renitency of the body A, to be moved with VOL. I. C

a ve

a velocity as a 1000 times C, it will move on with that velocity; which state of motion is now as much to be confidered as its ftate, as the former reft was: and it will just refift as much to be moved with a velocity as 2000 times C, or to have the velocity C another thousand times increased, as it did at first; or to be brought back again, from moving with the velocity 1000 C, to reft, as it did to be brought from reft to move with that velocity. In a word, as long as a change is poffible, which is always and endlefsly, fo long muft it refift; and it must refift equal changes equally: which was exactly the refiftance it was endued with, before any change was effected in it at all, and before any force was impreffed upon it at all. So that this refiftance cannot be impaired, augmented, or any way altered, by any new force impreffed ab extra. Which is already a strong symptom that resistance to a change of its ftate is of the nature of matter, as infeparable from it as folidity or extension i fince as long as the folid extenfion, that is the quantity of matter, in the body A, remains the fame, this immutability of its refiftance must be fuppofed, if it is at all refifting matter. XIV. But

4

XIV. But yet farther, as this refiftance in matter to change its ftate cannot be ultimately taken off, leffened, or any way altered, by any force impreffed ab extra upon it; fo neither could it fubfift in matter jointly with any quality, power, conatus, or tendency to change its state. For firft, fuppofing it poffible that two contrary tendencies could be planted in matter; one, whereby it refifted a change of its state, in any poffible direction, and another, whereby it tended to change it; this would be to no effect, nor to any other purpose than doing and undoing. These two contrary conatus's would deftroy each other if equal; or if unequal, the ftronger would destroy the weaker, and the excess of it only would remain. So that the refiftance to a change would either prevail, and then it would be the fame thing as if no fuch contrary tendency had been planted in matter; or the conatus to a change of the prefent state would prevail, and then the remaining in any given ftate poffible would itfelf be impoffible; which is a thought full of contradiction (ƒ). Thus

C 2

(f) This is very inconceivable, and really a self-deftructive

Thus two contrary tendencies (fuppofing they could be both planted in the fame individual fubject, as matter) would have the fame effe upon each other, as two contrary quantities, a pofitive and a negative; or as two forces impreffed upon the fame body in oppofite directions; to wit, to cancel each other

ftructive fuppofition. For to be indefinently changing its state supposes really no change of state at all in the body; because no precedent state could then be of any poffible finite duration: otherwife, if it were permitted to become of any finite length, and deserve the name of a precedent ftate, there would not be an indefinent change effected; or the body would have a tendency to preserve its state for some time, contrary to the hypothefis. To suppose an infinitely quick change of ftate, from reft to motion, and from motion to reft, is to fuppofe abfolute reft only. For when motion was but nascent, reft would be again induced, because the inceffant tendency to change inceffantly takes effect: and before reft were fettled, motion, for the fame reafon, ought to begin. So that, as was faid, this notion deftroys itself. How remarkable is this co-incidence, when the only fuppofition that could serve a sceptick's turn, of neceffity defeats itself! For if this tendency to change its state is the ftronger of the two, it muft overcome the other at all times, and infer the contradiction fhewn, in spite of all evasions: and the con clufion is, that such a superier tendency cannot be planted in matter.

mutually.

mutually. For a refistance to a change of ftate would refift a conatus toward it, in any poffible direction, by N° 5 and 1 1.

XV. This would be the refult, if it were poffible, that two contrary conatus's could be planted in matter at once: but that is really impoffible and contradictory. For that a particle, or atom of matter (and the reafon is the fame in any affigned quantity) should have a tendency to move in any one given direction, and at the same time that it fhould have another tendency not to move in that, or any other direction, is to have a tendency, and not to have it, at once. Two fuch contrary and inconfiftent tendencies, planted at once in one and the fame individual subject, is a notion destructive of itself; and therefore not to be effected by infinite power: for to effect impoffibilities is not the object of any power. The argument is the fame, whether the first state of the body is supposed rest or motion: for if it is fuppofed firft moving, it cannot have a tendency to move in that direction only, and with that particular degree of velocity only; and yet have a tendency to move in another direction, C 3

and