Prop. I. No positive quality possessed by a false idea is removed by the presence of what is true, in virtue of its being true.
Proof.- Falsity consists solely in the privation of knowledge which inadequate ideas involve (II:xxxv.), nor have they any positive quality on account of which they are called false (II:xxxiii.); contrariwise, in so far as they are referred to God, they are true (II:xxxii.). Wherefore, if the positive quality possessed by a false idea were removed by the presence of what is true, in virtue of its being true, a true idea would then be removed by itself, which (IV:iii.) is absurd. Therefore, no positive quality possessed by a false idea, &c. Q.E.D.
Note.- This proposition is more clearly understood from II:xvi.Coroll.ii.
For imagination is an idea, which indicates rather the present disposition of the human body than the nature of the external body; not indeed distinctly, but confusedly; whence it comes to pass, that the mind is said to err. For instance, when we look at the sun, we conceive that it is distant from us about two hundred feet; in this judgment we err, so long as we are in ignorance of its true distance; when its true distance is known, the error is removed, but not the imagination; or, in other words, the idea of the sun, which only explains tho nature of that luminary, in so far as the body is affected thereby: wherefore, though we know the real distance, we shall still nevertheless imagine the sun to be near us. For, as we said in III:xxxv.note, we do not imagine the sun to be so near us, because we are ignorant of its true distance, but because the mind conceives the magnitude of the sun to the extent that the body is affected thereby. Thus, when the rays of the sun falling on the surface of water are reflected into our eyes, we imagine the sun as if it were in the water, though we are aware of its real position; and similarly other imaginations, wherein the mind is deceived whether they indicate the natural disposition of the body, or that its power of activity is increased or diminished, are not contrary to the truth, and do not vanish at its presence. It happens indeed that, when we mistakenly fear an evil, the fear vanishes when we hear the true tidings; but the contrary also happens, namely, that we fear an evil which will certainly come, and our fear vanishes when we hear false tidings; thus imaginations do not vanish at the presence of the truth, in virtue of its being true, but because other imaginations, stronger than the first, supervene and exclude the present existence of that which we imagined, as I have shown in II:.xvii.
Prop. II. We are only passive, in so far as we are apart of Nature, which cannot be conceived by itself without other parts.
Proof.- We are said to be passive, when something arises in us, whereof we are only a partial cause (III:Def.ii.), that is (III:Def.i.), something which cannot be deduced solely from the laws of our nature. We are passive therefore in so far as we are a part of Nature, which cannot be conceived by itself without other parts. Q.E.D.
Prop. III. The force whereby a man persists in existing is limited, and is infinitely surpassed by the power of external causes.
Proof.-This is evident from the axiom of this part. For, when man is given, there is something else - say A - more powerful; when A is given, there is something else - say B - more powerful than A, and so on to infinity; thus the power of man is limited by the power of some other thing, and is infinitely surpassed by the power of external causes. Q.E.D.
Prop. IV. It is impossible, that man should not be a part of Nature, or that he should be capable of undergoing no changes, save such as can be understood through his nature only as their adequate cause.
Proof.- The power, whereby each particular thing, and consequently man, preserves his being, is the power of God or of Nature (I:xxiv.Coroll.); not in so far as it is infinite, but in so far as it can be explained by the actual human essence (III:vii.). Thus the power of man, in so far as it is explained through his own actual essence, is a part of the infinite power of God or Nature, in other words, of the essence thereof (I:xxxiv.). This was our first point. Again, if it were possible, that man should undergo no changes save such as can be understood solely through the nature of man, it would follow that he would not be able to die, but would always necessarily exist; this would be the necessary consequence of a cause whose power was either finite or infinite; namely, either of man's power only, inasmuch as he would be capable of removing from himself all changes which could spring from external causes; or of the infinite power of Nature, whereby all individual things would be so ordered, that man should be incapable of undergoing any changes save such as tended towards his own preservation. But the first alternative is absurd (by the last Prop., the proof of which is universal, and can be applied to all individual things). Therefore, if it be possible, that man should not be capable of undergoing any changes, save such as can be explained solely through his own nature, and consequently that he must always (as we have shown) necessarily exist; such a result must follow from the infinite power of God, and consequently (I:xvi.) from the necessity of the divine nature, in so far as it is regarded as affected by the idea of any given man, the whole order of nature as conceived under the attributes of extension and thought must be deducible. It would therefore follow (I:xxi.) that man is infinite, which (by the first part of this proof) is absurd.
It is, therefore, impossible, that man should not undergo any changes save those whereof he is the adequate cause. Q.E.D.
Corollary.- Hence it follows, that man is necessarily always a prey to his passions, that he follows and obeys the general order of nature, and that he accommodates himself thereto, as much as the nature of things demands.
