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paragraph becomes plain also from considering that resistance is the fame with re-action; for since action and re-action are equal, the re-action of matter may still be greater and greater, as the action upon it is greater and greater.

XIII. But contrarily, if we consider the fame quantity of matter or body A, absolutely, and without any respect to a fixt state, the resistance of it is immutable, and always as much the fame, as the solidity or extension of it: so that it is impossible that any force impressed upon it ab extra, should take it ultimately off, or lessen it, or encrease itj or, in a word, make it other than it always was, before such force was impressed. 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 persevere in that new state, as in the former: and that resistance again may be overcome, and a new state of motion or rest induced upon it; yet it will as obstinately continue in that state, as in any of the other two. And so on endlefly. If any force ab extra overcomes the renitency of the body A, to be moved with

Vol. L C avea velocity as a iooo times C, it will move oft with that velocity; which state of motion is now as much to be considered as its slate, as the former rest was: and it will just resist 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 iooo C, to rest, as it did to be brought from rest to movu with that velocity. In a word, as long as a change is possiblet which is always and endlessly, so long must it resist j and it must refist equal changes equally: which was exactly the resistance it was endued with, before any change was effected in it at all, and before any force was impressed upon it at all. So that this resistance cannot be impaired, augmented, or any way altered, by any new force impressed ab extra. Which is already a strong symptom that resistance to a change pf its state is of the nature of matter, as inseparable from it as solidity or extension j since as long as the solid extension, that is the quantity of matter, in the body A, remains the fame, this immutability of its resistance most be supposed, if it is at all resisting matter. 4 XIV. But

XIV. But yet farther, as this resistance in matter to change its state cannot be ultimately taken off, lessened, or anyway altered, by any force impressed ab extra upon it; so neither could it subsist in matter jointly with any quality, power, conatus, or tendency to change its state. For first, supposing it possible that two contrary tendencies could be planted in matter; one, whereby it resisted a change of its state, in any possible 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 destroy each other if equal; or if unequal, the stronger would destroy the weaker, and the excess of it only would remain. So that the resistance to a change would either prevail, and then it would be the fame thing as if no such contrary tendency had been planted in matter; or the conatus to a change of the present state would prevail, and then the remaining in any given state possible would itself be impossible; which is a thought full of contradiction (f).

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(f) This is very inconceivable, aud really a self-destructive Thus two contrary tendencies (supposing they could be both planted in the same individual subject, as matter) would have the fame efl£?2 upon each other, as two contrary quantities, a positive and a negative; or as two forces impressed upon the same body in opposite directions; to wit, to cancel each other

structive supposition. For to be indesinently changing its state supposes really no change of state at all in the body; because no precedent state could then be of any possible finite duration: otherwise, if it were permitted to become of any finite length, and deserve the name of a precedent state, there would not be an indesinent change effected; or the body would have a tendency to preserve its state for some time, contrary to the hypothesis. To suppose an infinitely quick change of state, from rest to motion, and from motion to rest, b to suppose absolute rest only. For when motion was but nascent, rest would he again induced, because the incessant tendency to change incessantly takes effect: and before reft were settled, motion, for the fame reason, ought to begin. So that, as. was faid, this notion destroys itself. How remarkable is this co-incidence, when the only supposition that could serve a sceptick's turn, of necessity defeats itself! For if this tendency to change its state is the stronger of the two, it must overcome the other at all times, and infer the contradiction shewn, in spite of all evasions: and the con. elusion is, Otatsucb esuptritr tendency cannot be planted in matter,



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mutually. For a resistance to a change of state would resist a conatus toward it, in any possible direction, by N° 5 and 11,

XV. This would be the result, if it were possible, that two contrary conatus's could be planted in matter at once: but that is really impossible and contradictory. For that a particle, or atom of matter (and the reason is the same in any assigned quantity) should have a tendency to move in any one given direction, and at the fame time that it mould 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 such contrary and inconsistent 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 impossibilities 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 supposed first 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^

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