CHAPTER X.

OF POWER AND ACT.

1. Power and cause are the same thing.—2. An act is produced at the same instant in which the power is plenary.—3. Active and passive power are parts only of plenary power.—4. An act, when said to be possible.—5. An act necessary and contingent, what.—6. Active power consists in motion.—7. Cause, formal and final, what they are.

[Sidenote: Power and cause are the same thing.]

1. Correspondent to _cause_ and _effect_, are POWER and ACT; nay, those and these are the same things; though, for divers considerations, they have divers names. For whensoever any agent has all those accidents which are necessarily requisite for the production of some effect in the patient, then we say that agent has _power_ to produce that effect, if it be applied to a patient. But, as I have shewn in the precedent chapter, those accidents constitute the efficient cause; and therefore the same accidents, which constitute the efficient cause, constitute also the _power_ of the agent. Wherefore the _power of the agent_ and the _efficient cause_ are the same thing. But they are considered with this difference, that _cause_ is so called in respect of the effect already produced, and power in respect of the same effect to be produced hereafter; so that _cause_ respects the past, _power_ the future time. Also, the _power of the agent_ is that which is commonly called _active power_.

In like manner, whensoever any patient has all those accidents which it is requisite it should have, for the production of some effect in it, we say it is in the _power_ of that patient to produce that effect, if it be applied to a fitting agent. But those accidents, as is defined in the precedent chapter, constitute the material cause; and therefore the _power of the patient_, commonly called _passive power_, and _material cause_, are the same thing; but with this different consideration, that in cause the past time, and in power the future, is respected. Wherefore the power of the agent and patient together, which may be called entire or _plenary power_, is the same thing with _entire cause_; for they both consist in the sum or aggregate of all the accidents, as well in the agent as in the patient, which are requisite for the production of the effect. Lastly, as the accident produced is, in respect of the cause, called an effect, so in respect of the power, it is called an _act_.

[Sidenote: An act is produced at the same instant in which the power is plenary.]

2. As therefore the effect is produced in the same instant in which the cause is entire, so also every act that may be produced, is produced in the same instant in which the power is plenary. And as there can be no effect but from a sufficient and necessary cause, so also no act can be produced but by sufficient power, or that power by which it could not but be produced.

[Sidenote: Active and passive power are parts only of plenary power.]

3. And as it is manifest, as I have shewn, that the efficient and material causes are severally and by themselves parts only of an entire cause, and cannot produce any effect but by being joined together, so also power, active and passive, are parts only of plenary and entire power; nor, except they be joined, can any act proceed from them; and therefore these powers, as I said in the first article, are but conditional, namely, _the agent has power, if it be applied to a patient; and the patient has power, if it be applied to an agent_; otherwise neither of them have power, nor can the accidents, which are in them severally, be properly called powers; nor any action be said to be possible for the power of the agent alone or of the patient alone.

[Sidenote: An act, when said to be possible.]

4. For that is an impossible act, for the production of which there is no power plenary. For seeing plenary power is that in which all things concur, which are requisite for the production of an act, if the power shall never be plenary, there will always be wanting some of those things, without which the act cannot be produced; wherefore that act shall never be produced; that is, that act is IMPOSSIBLE: and every act, which is not impossible, is POSSIBLE. Every act, therefore, which is possible, shall at some time be produced; for if it shall never be produced, then those things shall never concur which are requisite for the production of it; wherefore that act is _impossible_, by the definition; which is contrary to what was supposed.

[Sidenote: An act necessary and contingent, what.]

5. A _necessary act_ is that, the production whereof it is impossible to hinder; and therefore every act, that shall be produced, shall necessarily be produced; for, that it shall not be produced, is impossible; because, as is already demonstrated, every possible act shall at some time be produced; nay, this proposition, _what shall be, shall be_, is as necessary a proposition as this, _a man is a man_.

But here, perhaps, some man may ask whether those future things, which are commonly called _contingents_, are necessary. I say, therefore, that generally all contingents have their necessary causes, as is shewn in the preceding chapter; but are called contingents in respect of other events, upon which they do not depend; as the rain, which shall be tomorrow, shall be necessary, that is, from necessary causes; but we think and say it happens by chance, because we do not yet perceive the causes thereof, though they exist now; for men commonly call that _casual_ or _contingent_, whereof they do not perceive the necessary cause; and in the same manner they used to speak of things past, when not knowing whether a thing be done or no, they say it is possible it never was done.

Wherefore, all propositions concerning future things, contingent or not contingent, as this, _it will rain tomorrow_, or this, _tomorrow the sun will rise_, are either necessarily true, or necessarily false; but we call them contingent, because we do not yet know whether they be true or false; whereas their verity depends not upon our knowledge, but upon the foregoing of their causes. But there are some, who though they confess this whole proposition, _tomorrow it will either rain, or not rain_, to be true, yet they will not acknowledge the parts of it, as, _tomorrow it will rain_, or, _tomorrow it will not rain_, to be either of them true by itself; because they say neither this nor that is true _determinately_. But what is this _determinately true_, but true upon our knowledge, or evidently true? And therefore they say no more but that it is not yet known whether it be true or no; but they say it more obscurely, and darken the evidence of the truth with the same words, with which they endeavour to hide their own ignorance.

[Sidenote: Active power consists in motion.]

6. In the 9th article of the preceding chapter, I have shewn that the efficient cause of all motion and mutation consists in the motion of the agent, or agents; and in the first article of this chapter, that the power of the agent is the same thing with the efficient cause. From whence it may be understood, that all active power consists in motion also; and that power is not a certain accident, which differs from all acts, but is, indeed, an act, namely, motion, which is therefore called power, because another act shall be produced by it afterwards. For example, if of three bodies the first put forward the second, and this the third, the motion of the second, in respect of the first which produceth it, is the act of the second body; but, in respect of the third, it is the active power of the same second body.

[Sidenote: Cause, formal and final, what they are.]

7. The writers of metaphysics reckon up two other causes besides the _efficient_ and _material_, namely, the ESSENCE, which some call the _formal cause_, and the END, or _final cause_; both which are nevertheless efficient causes. For when it is said the essence of a thing is the cause thereof, _as to be rational is the cause of man_, it is not intelligible; for it is all one, as if it were said, _to be a man is the cause of man_; which is not well said. And yet the knowledge of the _essence_ of anything, is the cause of the knowledge of the thing itself; for, if I first know that a thing is _rational_, I know from thence, that the same is _man_; but this is no other than an efficient cause. A _final cause_ has no place but in such things as have sense and will; and this also I shall prove hereafter to be an efficient cause.

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