P2: The Body cannot determine the Mind to thinking, and the Mind cannot determine the Body to motion, to rest or to anything else (if there is anything else).

Dem.: All modes of thinking have God/Nature for a cause, insofar as he is a thinking thing, and not insofar as he is explained by another attribute (by IIP6). So what determines the Mind to thinking is a mode of thinking and not of Extension, i.e. (by IID1), it is not the Body. This was the first point.

Next, the motion and rest of the Body must arise from another body, which has also been determined to motion or rest by another; and absolutely, whatever arises in the body must have arisen from God/Nature insofar as he is considered to be affected by some mode of Extension, and not insofar as he is considered to be affected by some mode of thinking (also by IIP6), i.e., it cannot arise from the Mind, which (by IIP11) is a mode of thinking. This was the second point. Therefore, the Body cannot determine the Mind, etc., q.e.d.

Schol.: These things are more clearly understood from what is said in IIP7 S, viz. that the Mind and the Body are one and the same thing, which is conceived now under the attribute of Thought, now under the attribute of Extension.

The result is that the order, or connection, of things is one, whether nature is conceived under this attribute or that; hence the order of actions and passions of our Body is, by nature, at one with the order of actions and passions of the Mind. This is also evident from the way in which we have demonstrated IIP12.

But although these things are such that no reason for doubt remains, still, I hardly believe that men can be induced to consider them fairly unless I confirm them by experience.

They are so firmly persuaded that the Body now moves, now is at rest, solely from the Mind’s command, and that it does a great many things which depend only on the Mind’s will and its art of thinking.

For indeed, no one has yet determined what the Body can do, i.e., experience has not yet taught anyone what the Body can do from the laws of nature alone, insofar as nature is only considered to be corporeal, and what the body can do only if it is determined by the Mind. For no one has yet come to know the structure of the Body so accurately that he could explain all its functions—not to mention that many things are observed in the lower Animals that far surpass human ingenuity, and that sleepwalkers do a great many things in their sleep that they would not dare to awake. This shows well enough that the Body itself, simply from the laws of its own nature, can do many things which its Mind wonders at.

Again, no one knows how, or by what means, the Mind moves the body, nor how many degrees of motion it can give the body, nor with what speed it can move it. So it follows that when men say that this or that action of the Body arises from the Mind, which has dominion over the Body, they do not know what they are saying, and they do nothing but confess, in fine sounding words, that they are ignorant of the true cause of that action, and that they do not wonder at it.

But they will say [i] that—whether or not they know by what means the Mind moves the Body—they still know by experience that unless the human Mind were capable of thinking, the Body would be inactive.9 And then [ii], they know by experience, that it is in the Mind’s power alone both to speak and to be silent,10 and to do many other things which they therefore believe depend on the Mind’s decision.

[i] As far as the first {objection} is concerned, I ask them, does not experience also teach that if, on the other hand, the Body is inactive, the Mind is at the same time incapable of thinking? For when the Body is at rest in sleep, the Mind at the same time remains senseless with it, nor does it have the power of thinking, as it does when awake. And then I believe everyone has found by experience that the Mind is not always equally capable of thinking of the same object, but that as the Body is more susceptible to having the image of this or that object aroused in it, so the Mind is more capable of regarding this or that object.

They will say, of course, that it cannot happen that the causes of buildings, of paintings, and of things of this kind, which are made only by human skill, should be able to be deduced from the laws of nature alone, insofar as it is considered to be only corporeal; nor would the human Body be able to build a temple, if it were not determined and guided by the Mind.

But I have already shown that they do not know what the Body can do, or what can be deduced from the consideration of its nature alone, and that they know from experience that a great many things happen from the laws of nature alone which they never would have believed could happen without the direction of the Mind—such as the things sleepwalkers do in their sleep, which they wonder at while they are awake.

I add here the very structure of the human Body, which, in the ingenuity of its construction, far surpasses anything made by human skill—not to mention that I have shown above, that

infinitely many things follow from nature, under whatever attribute it may be considered.

[ii] As for the second {objection}, human affairs, of course, would be conducted far more happily if it were equally in man’s power to be silent and to speak. But experience teaches all too plainly that men have nothing less in their power than their tongue, and can do nothing less than moderate their appetites.

That is why most men believe that we do freely only those things we have a weak inclination toward (because the appetite for these things can easily be reduced by the memory of another thing which we frequently recollect), but that we do not at all do freely those things we seek by a strong affect, which cannot be calmed by the memory of another thing. But if they had not found by experience that we do many things we afterwards repent, and that often we see the better and follow the worse (viz. when we are torn by contrary affects), nothing would prevent them from believing that we do all things freely.

So the infant believes he freely wants the milk; the angry child that he wants vengeance; and the timid, flight. So the drunk believes it is from a free decision of the Mind that he speaks the things he later, when sober, wishes he had not said. So the madman, the chatterbox, the child, and a great many people of this kind believe they speak from a free decision of the Mind, when really they cannot contain their impulse to speak.

So experience itself, no less clearly than reason, teaches that men believe themselves free because they are conscious of their own actions, and ignorant of the causes by which they are determined, that the decisions of the Mind are nothing but the appetites themselves, which therefore vary as the disposition of the Body varies. For each one governs everything from his affect; those who are torn by contrary affects do not know what they want, and those who are not moved by any affect are very easily driven here and there.11 All these things, indeed, show clearly that both the decision of the Mind and the appetite and the determination of the Body by nature exist together—or rather are one and the same thing, which we call a decision when it is considered under, and explained through, the attribute of Thought, and which we call a determination when it is considered under the attribute of Extension and deduced from the laws of motion and rest. This will be still more clearly evident from what must presently be said.

For there is something else I wish particularly to note here, that we can do nothing from a decision of the Mind unless we recollect it. E.g., we cannot speak a word unless we recollect it. And it is not in the free power of the Mind to either recollect a thing or forget it.12 So this only is believed to be in the power of the Mind—that from the Mind’s decision alone we can either be silent about or speak about a thing we recollect.

But when we dream that we speak, we believe that we speak from a free decision of the Mind—and yet we do not speak, or, if we do, it is from a spontaneous motion of the Body.

And we dream that we conceal certain things from men, and this by the same decision of the Mind by which, while we wake, we are silent about the things we know. We dream, finally, that, from a decision of the Mind, we do certain things we do not dare to do while we wake.

So I should very much like to know whether there are in the Mind two kinds of decisions— those belonging to our fantasies and those that are free? And if we do not want to go that far in our madness, it must be granted that this decision of the Mind which is believed to be free is not distinguished by the imagination itself, or the memory, nor is it anything beyond that affirmation which the idea, insofar as it is an idea, necessarily involves (see IIP49). And so these decisions of the Mind arise by the same necessity as the ideas of things that actually exist.

Those, therefore, who believe that they either speak or are silent, or do anything from a free decision of the Mind, dream with open eyes.