Preface
Human infirmity in moderating and checking the emotions I name bondage；for，when a man is a prey to his emotions，he is not his own master，but lies at the mercy of fortune；so much so，that he is often compelled，while seeing that which is better for him，to follow that which is worse。Why this is so，and what is good or evil in the emo-tions，I propose to show in this part of my treatise。But，before I begin，it would be well to make a few prefatory observations on perfection and imperfection，good and evil。
When a man has purposed to make a given thing，and has brought it to perfection，his work will be pronounced perfect，not only by himself，but by everyone who rightly knows，or thinks that he knows，the intention and aim of its author。For instance，sup-pose anyone sees a work（which I assume to be not yet completed），and knows that the aim of the author of that work is to build a house，he will call the work imperfect；he will，on the other hand，call it perfect，as soon as he sees that it is carried through to the end，which its author had purposed for it。But if a man sees a work，the like where-of he has never seen before，and if he knows not the intention of the artificer，he plainly cannot know，whether that work be perfect or imperfect。Such seems to be the primary meaning of these terms。
But，after men began to form general ideas，to think out types of houses，build-ings，towers，and to prefer certain types to others，it came about，that each man called perfect that which he saw agree with the general idea he had formed of the thing in ques-tion，and called imperfect that which he saw agree less with his own preconceived type，even though it had evidently been completed in accordance with the idea of its artificer。This seems to be the only reason for calling natural phenomena，which，indeed，are not made with human hands，perfect or imperfect；for men are wont to form general ideas of things natural，no less than of things artificial，and such ideas they hold as types，be-lieving that nature（who they think does nothing without an object）has them in view，and has set them as types before herself。Therefore，when they behold something in na-ture，which does not wholly conform to the preconceived type which they have formed of the thing in question，they say that nature has fallen short or has blundered，and has left her work incomplete。Thus we see that men are wont to style natural phenomena perfect or imperfect rather from their own prejudices，than from true knowledge of what they pronounce upon。
Now we showed in the Appendix to Part I。，that nature does not work with an end in view。For the eternal and infinite being，which we call God or Nature，acts by the same necessity as that whereby it exists。For we have shown，that by the same necessity of its nature，whereby it exists，it likewise works。The reason or cause why God or Na-ture exists，and the reason why he acts，are one and the same。Therefore，as he does not exist for the sake of an end，so neither does he act for the sake of an end；of his ex-istence and of his action there is neither origin nor end。Wherefore，a cause which is called final is nothing else but human desire，in so far as it is considered as the origin or cause of anything。For example，when we say that to be inhabited is the final cause of this or that house，we mean nothing more than that a man，conceiving the conveniences of household life，had a desire to build a house。Wherefore，the being inhabited，in so far as it is regarded as a final cause，is nothing else but this particular desire，which is really the efficient cause；it is regarded as the primary cause，because men are generally ignorant of the causes of their desires。They are，as I have often said already，conscious of their own actions and appetites，but ignorant of the causes whereby they are deter-mined to any particular desire。Therefore，the common saying that nature sometimes falls short，or blunders，and produces things which are imperfect，I set down among the glosses treated of in the Appendix to Part I。
Perfection and imperfection，then，are in reality merely modes of thinking，or no-tions which we form from a comparison among one another of individuals of the same species；hence I said above，that by reality and perfection I mean the same thing。For we are wont to refer all the individual things in nature to one genus，which is called the highest genus，namely，to the category of being，whereto absolutely all individuals in nature belong。Thus，in so far as we refer the individuals in nature to this category，and comparing them one with another，find that some possess more of being or reality than others，we，to this extent，say，that some are more perfect than others。Again，in so far as we attribute to them anything implying negation-as term，end，infirmity，etc。，-we，to this extent，call them imperfect，because they do not affect our mind so much as the things which we call perfect，not because they have any intrinsic deficiency，or be-cause nature has blundered。For nothing lies within the scope of a thing s nature，save that which follows from the necessity of the nature of its efficient cause，and whatsoever follows from the necessity of the nature of its efficient cause necessarily comes to pass。
As for the terms good and bad，they indicate no positive quality in things regarded in themselves，but are merely modes of thinking，or notions which we form from the comparison of things one with another。Thus one and the same thing can be at the same time good，bad，and indifferent。For instance，music is good for him that is melanchol-y，bad for him that mourns；for him that is deaf，it is neither good nor bad。Never the-less，though this be so，the terms should still be retained。For，inasmuch as we desire to form an idea of man as a type of human nature which we may hold in view，it will be useful for us to retain the terms in question，in the sense I have indicated。
In what follows，then，I shall mean by“good”that，which we certainly know to be a means of approaching more nearly to the type of human nature，which we have set be-fore ourselves；by“bad，”that which we certainly know to be a hindrance to us in ap-proaching the said type。Again，we shall say that men are more perfect，or more imper-fect，in proportion as they approach more or less nearly to the said type。For it must be specially remarked that，when I say that a man passes from a lesser to a greater perfec-tion，or vice versa，I do not mean that he is changed from one essence or reality to an-other；for instance，a horse would be as completely destroyed by being changed into a man，as by being changed into an insect。What I mean is，that we conceive the thing s power of action，in so far as this is understood by its nature，to be increased or dimin-ished。Lastly，by perfection in general I shall，as I have said，mean reality-in other words，each thing s essence，in so far as it exists，and operates in a particular manner，and without paying any regard to its duration。For no given thing can be said to be more perfect，because it has passed a longer time in existence。The duration of things cannot be determined by their essence，for the essence of things involves no fixed and definite period of existence；but everything，whether it be more perfect or less perfect，will al-ways be able to persist in existence with the same force wherewith it began to exist；wherefore，in this respect，all things are equal。
Definitions
1.By good I mean that which we certainly know to be useful to us。
2.By evil I mean that which we certainly know to be a hindrance to us in the at-tainment of any good。
3.Particular things I call contingent in so far as，while regarding their essence on-ly，we find nothing therein，which necessarily asserts their existence or excludes it。
4.Particular things I call possible in so far as，while regarding the causes whereby they must be produced，we know not，whether such causes be determined for producing them。
5.By conflicting emotions I mean those which draw a man in different directions，though they are of the same kind，such as luxury and avarice，which are both species of love，and are contraries，not by nature，but by accident。
6.What I mean by emotion felt towards a thing，future，present，and past，I ex-plained in Part 3，Prop。18，notes 1.and 2.，which see。
（But I should here also remark，that we can only distinctly conceive distance of space or time up to a certain definite limit；that is，all objects distant from us more than two hundred feet，or whose distance from the place where we are exceeds that which we can distinctly conceive，seem to be an equal distance from us，and all in the same plane；so also objects，whose time of existing is conceived as removed from the present by a longer interval than we can distinctly conceive，seem to be all equally distant from the present，and are set down，as it were，to the same moment of time。）
7.By an end，for the sake of which we do something，I mean a desire。
8.By virtue and power I mean the same thing；that is，virtue，in so far as it is re-ferred to man，is a man s nature or essence，in so far as it has the power of effecting what can only be understood by the laws of that nature。
Axiom
There is no individual thing in nature，than which there is not another more power-ful and strong。Whatsoever thing be given，there is something stronger whereby it can be destroyed。
Propositions
PROP。1.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，nor have they any positive quality on account of which they are called false；contrariwise，in so far as they are referred to God，they are true。Wherefore，if the posi-tive 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 is absurd。
PROP。2.We are only passive，in so far as we are part 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，that is，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。
PROP。3.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。
PROP。4.It is impossible，that man should not be apart 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，pre-serves his being，is the power of God or of Nature；not in so far as it is infinite，but in so far as it can be explained by the actual human essence。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。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 ex-ternal 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 ten-ded towards his own preservation。But the first alternative is absurd。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 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 that man is infinite，which is absurd。It is，therefore，impossible，that man should not un-dergo any changes save those whereof he is the adequate cause。
Corollary。-Hence it follows，that man is necessarily always a prey to his pas-sions，that he follows and obeys the general order of nature，and that he accommodates himself thereto，as much as the nature of things demands。
PROP。5.The power and increase of every passion，and its persistence in existing are not defined by the power，whereby we ourselves endeavour to persist in existing，but by the power of an external cause compared with our own。
Proof。-The essence of a passion cannot be explained through our essence alone，that is，the power of a passion cannot be defined by the power，whereby we ourselves endeavour to persist in existing，but must necessarily be defined by the power of an ex-ternal cause compared with our own。
PROP。6.The force of any passion or emotion can overcome the rest of a man s ac-tivities or power，so that the emotion becomes obstinately fixed to him。
Proof。-The force and increase of any passion and its persistence in existing are defined by the power of an external cause compared with our own；therefore it can over-come a man s power。
PROP。7.An emotion can only be controlled or destroyed by another emotion con-trary thereto，and with more power for controlling emotion。
Proof。-Emotion，in so far as it is referred to the mind，is an idea，whereby the mind affirms of its body a greater or less force of existence than before。When，there-fore，the mind is assailed by any emotion，the body is at the same time affected with a modification whereby its power of activity is increased or diminished。Now this modifica-tion of the body receives from its cause the force for persistence in its being；which force can only be checked or destroyed by a bodily cause，in virtue of the body being affected with a modification contrary to and stronger than itself；wherefore the mind is affected by the idea of a modification contrary to，and stronger than the former modification，in oth-er words，the mind will be affected by an emotion contrary to and stronger than the for-mer emotion，which will exclude or destroy the existence of the former emotion；thus an emotion cannot be destroyed nor controlled except by a contrary and stronger emotion。
Corollary。-An emotion，in so far as it is referred to the mind，can only be con-trolled or destroyed through an idea of a modification of the body contrary to，and stron-ger than，that which we are undergoing。For the emotion which we undergo can only be checked or destroyed by an emotion contrary to，and stronger than，itself，in other words，only by an idea of a modification of the body contrary to，and stronger than，the modification which we undergo。
PROP。8.The knowledge of good and evil is nothing else but the emotions of pleasure or pain，in so far as we are conscious thereof。
Proof。-We call a thing good or evil，when it is of service or the reverse in preser-ving our being，that is，when it increases or diminishes，helps or hinders，our power of activity。Thus，in so far as we perceive that a thing affects us with pleasure or pain，we call it good or evil；wherefore the knowledge of good and evil is nothing else but the idea of the pleasure or pain，which necessarily follows from that pleasurable or painful emo-tion。But this idea is united to the emotion in the same way as mind is united to body；that is，there is no real distinction between this idea and the emotion or idea of the mod-ification of the body，save in conception only。Therefore the knowledge of good and evil is nothing else but the emotion，in so far as we are conscious thereof。
PROP。9.An emotion，whereof we conceive the cause to be with us at the present time，is stronger than if we did not conceive the cause to be with us。
Proof。-Imagination or conception is the idea，by which the mind regards a thing as present，but which indicates the disposition of the body rather than the nature of the external thing。An emotion is therefore an imagination，in so far as it indicates the dis-position of the body。But an imagination is stronger，so long as we conceive nothing which excludes the present existence of the external object；wherefore an emotion is also stronger or more intense，when we conceive the cause to be with us at the present time，than when we do not conceive the cause to be with us。
Corollary。-The image of something past or future，that is，of a thing which we re-gard as in relation to time past or time future，to the exclusion of time present，is，when other conditions are equal，weaker than the image of something present；consequently an emotion felt towards what is past or future is less intense，other conditions being e-qual，than an emotion felt towards something present。
PROP。10.Towards something future，which we conceive as close at hand，we are affected more intensely，than if we conceive that its time for existence is separated from the present by a longer interval；so too by the remembrance of what we conceive to have not long passed away we are affected more intensely，than if we conceive that it has long passed away。
Proof。-In so far as we conceive a thing as close at hand，or not long passed away，we conceive that which excludes the presence of the object less，than if its period of fu-ture existence were more distant from the present，or if it had long passed away；there-fore we are，so far，more intensely affected towards it。
PROP。11.An emotion towards that which we conceive as necessary is，when oth-er conditions are equal，more intense，than an emotion towards that which impossible，or contingent，or non-necessary。
Proof。-In so far as we conceive a thing to be necessary，we，to that extent，affirm its existence；on the other hand we deny a thing s existence，in so far as we conceive it not to be necessary；wherefore an emotion towards that which is necessary is，other condi-tions being equal，more intense than an emotion towards that which is non-necessary。
PROP。12.An emotion towards a thing，which we know not to exist at the present time，and which we conceive as possible，is more intense，other conditions being e-qual，than an emotion towards a thing contingent。
Proof。-In so far as we conceive a thing as contingent，we are affected by the con-ception of some further thing，which would assert the existence of the former；but，on the other hand，we conceive certain things，which exclude its present existence。But，in so far as we conceive a thing to be possible in the future，we thereby conceive things which assert its existence，that is，things which promote hope or fear；wherefore an e-motion towards something possible is more vehement。
Corollary。-An emotion towards a thing，which we know not to exist in the pres-ent，and which we conceive as contingent，is far fainter，than if we conceive the thing to be present with us。
Proof。-Emotion towards a thing，which we conceive to exist，is more intense than it would be，if we conceived the thing as future，and is much more vehement，than if the future time be conceived as far distant from the present。Therefore an emotion to-wards a thing，whose period of existence we conceive to be far distant from the present，is far fainter，than if we conceive the thing as present；it is，nevertheless，more in-tense，than if we conceived the thing as contingent，wherefore an emotion towards a thing，which we regard as contingent，win be far fainter，than if we conceived the thing to be present with us。
PROP。13.Emotion towards a thing contingent，which we know not to exist in the present，is，other conditions being equal，fainter than an emotion towards a thing past。
Proof。-In so far as we conceive a thing as contingent，we are not affected by the image of any other thing，which asserts the existence of the said thing，but，on the other hand，we conceive certain things excluding its present existence。But，in so far as we conceive it in relation to time past，we are assumed to conceive something，which re-calls the thing to memory，or excites the image thereof，which is so far the same as re-garding it as present。Therefore an emotion towards a thing contingent，which we know does not exist in the present，is fainter，other conditions being equal，than an emotion towards a thing past。