Book III chapter 9

The soul of animals is characterized by two faculties¹, (a) the faculty² of discrimination which is the work of thought and sense, and (b) the faculty of originating local movement. Sense and mind we have now sufficiently³ examined. Let us next consider what it is in the soul which originates movement. Is it a single part of the soul separate either spatially⁴ or in definition? Or is it the soul as a whole? If it is a part, is that part different from those usually distinguished⁵ or already mentioned by us, or is it one of them? The problem at once presents itself, in what sense we are to speak of parts of the soul, or how many we should distinguish. For in a sense there is an infinity⁶ of parts: it is not enough to distinguish, with some thinkers, the calculative, the passionate⁷, and the desiderative, or with others the rational and the irrational⁸; for if we take the dividing lines followed by these thinkers we shall find parts far more distinctly separated from one another than these, namely those we have just mentioned: (1) the nutritive, which belongs both to plants and to all animals, and (2) the sensitive, which cannot easily be classed as either irrational or rational; further (3) the imaginative, which is, in its being, different from all, while it is very hard to say with which of the others it is the same or not the same, supposing we determine to posit⁹ separate parts in the soul; and lastly (4) the appetitive, which would seem to be distinct both in definition and in power from all hitherto enumerated¹⁰.

It is absurd to break up the last-mentioned faculty: as these thinkers do, for wish is found in the calculative part and desire and passion in the irrational; and if the soul is tripartite appetite will be found in all three parts. Turning our attention to the present object of discussion, let us ask what that is which originates local movement of the animal.

The movement of growth and decay, being found in all living things, must be attributed to the faculty of reproduction and nutrition, which is common to all: inspiration and expiration¹¹, sleep and waking, we must consider later: these too present much difficulty: at present we must consider local movement, asking what it is that originates forward movement in the animal.

That it is not the nutritive faculty is obvious; for this kind of movement is always for an end and is accompanied either by imagination or by appetite; for no animal moves except by compulsion unless it has an impulse towards or away from an object. Further, if it were the nutritive faculty, even plants would have been capable of originating such movement and would have possessed¹² the organs necessary to carry it out. Similarly it cannot be the sensitive faculty either; for there are many animals which have sensibility but remain fast and immovable throughout their lives.

If then Nature never makes anything without a purpose and never leaves out what is necessary (except in the case of mutilated or imperfect growths; and that here we have neither mutilation nor imperfection may be argued from the facts that such animals (a) can reproduce their species and (b) rise to completeness of nature and decay to an end), it follows that, had they been capable of originating forward movement, they would have possessed the organs necessary for that purpose. Further, neither can the calculative faculty or what is called ‘mind’ be the cause of such movement; for mind as speculative¹³ never thinks what is practicable, it never says anything about an object to be avoided or pursued, while this movement is always in something which is avoiding or pursuing an object. No, not even when it is aware of such an object does it at once enjoin¹⁴ pursuit or avoidance of it; e.g. the mind often thinks of something terrifying or pleasant without enjoining¹⁵ the emotion of fear. It is the heart that is moved (or in the case of a pleasant object some other part). Further, even when the mind does command and thought bids us pursue or avoid something, sometimes no movement is produced; we act in accordance with desire, as in the case of moral weakness. And, generally, we observe that the possessor of medical knowledge is not necessarily healing, which shows that something else is required to produce action in accordance with knowledge; the knowledge alone is not the cause. Lastly, appetite too is incompetent¹⁶ to account fully¹⁷ for movement; for those who successfully resist temptation have appetite and desire and yet follow mind and refuse to enact¹⁸ that for which they have appetite.

1 faculties   

n.能力( faculty的名词复数 )；全体教职员；技巧；院

参考例句：

• Although he's ninety, his mental faculties remain unimpaired. 他虽年届九旬，但头脑仍然清晰。
• All your faculties have come into play in your work. 在你的工作中，你的全部才能已起到了作用。 来自《简明英汉词典》

2 faculty   

n.才能；学院，系；(学院或系的)全体教学人员

参考例句：

• He has a great faculty for learning foreign languages.他有学习外语的天赋。
• He has the faculty of saying the right thing at the right time.他有在恰当的时候说恰当的话的才智。

3 sufficiently   

adv.足够地，充分地

参考例句：

• It turned out he had not insured the house sufficiently.原来他没有给房屋投足保险。
• The new policy was sufficiently elastic to accommodate both views.新政策充分灵活地适用两种观点。

4 spatially   

空间地，存在于空间地

参考例句：

• A well-defined array of stable fringes results and the field is spatially coherent. 结果得到一组完全确定的稳定条纹，而光场是空间相干的。
• The units are collaged together by a serial tectonic spatially and temporally. 这些构造单元是由构造原因，依一定的时空序列拼贴在一起的。

5 distinguished   

adj.卓越的，杰出的，著名的

参考例句：

• Elephants are distinguished from other animals by their long noses.大象以其长长的鼻子显示出与其他动物的不同。
• A banquet was given in honor of the distinguished guests.宴会是为了向贵宾们致敬而举行的。

6 infinity   

n.无限，无穷，大量

参考例句：

• It is impossible to count up to infinity.不可能数到无穷大。
• Theoretically,a line can extend into infinity.从理论上来说直线可以无限地延伸。

7 passionate   

adj.热情的，热烈的，激昂的，易动情的，易怒的，性情暴躁的

参考例句：

• He is said to be the most passionate man.据说他是最有激情的人。
• He is very passionate about the project.他对那个项目非常热心。

8 irrational   

adj.无理性的，失去理性的

参考例句：

• After taking the drug she became completely irrational.她在吸毒后变得完全失去了理性。
• There are also signs of irrational exuberance among some investors.在某些投资者中是存在非理性繁荣的征象的。

9 posit   

v.假定，认为

参考例句：

• If she needs salvation,she will posit a savior.如果她需要救助，她就会设想一个救助者。
• Other historians posit that she died of old age around 550 BC.别的史学家则认为她一直活到公元前550年左右才寿终正寝。

10 enumerated   

v.列举，枚举，数( enumerate的过去式和过去分词 )

参考例句：

• A spokesperson enumerated the strikers' demands. 发言人列数罢工者的要求。 来自《简明英汉词典》
• He enumerated the capitals of the 50 states. 他列举了50个州的首府。 来自《现代汉英综合大词典》

11 expiration   

n.终结，期满，呼气，呼出物

参考例句：

• Can I have your credit card number followed by the expiration date?能告诉我你的信用卡号码和它的到期日吗?
• This contract shall be terminated on the expiration date.劳动合同期满，即行终止。

12 possessed   

adj.疯狂的；拥有的，占有的

参考例句：

• He flew out of the room like a man possessed.他像着了魔似地猛然冲出房门。
• He behaved like someone possessed.他行为举止像是魔怔了。

13 speculative   

adj.思索性的，暝想性的，推理的

参考例句：

• Much of our information is speculative.我们的许多信息是带推测性的。
• The report is highly speculative and should be ignored.那个报道推测的成分很大，不应理会。

14 enjoin   

v.命令；吩咐；禁止

参考例句：

• He enjoined obedience on the soldiers.他命令士兵服从。
• The judge enjoined him from selling alcohol.法官禁止他卖酒。

15 enjoining   

v.命令( enjoin的现在分词 )

参考例句：

• Then enjoining him to keep It'strictly confidential, he told him the whole story. 叮嘱他严守秘密，然后把这事讲出来。 来自汉英文学 - 围城
• The act or an instance of enjoining; a command, a directive, or an order. 命令的动作或例子；命令，指令或训谕。 来自互联网

16 incompetent   

adj.无能力的，不能胜任的

参考例句：

• He is utterly incompetent at his job.他完全不能胜任他的工作。
• He is incompetent at working with his hands.他动手能力不行。

17 fully   

adv.完全地，全部地，彻底地；充分地

参考例句：

• The doctor asked me to breathe in,then to breathe out fully.医生让我先吸气，然后全部呼出。
• They soon became fully integrated into the local community.他们很快就完全融入了当地人的圈子。

18 enact   

vt.制定(法律)；上演，扮演

参考例句：

• The U.S. Congress has exclusive authority to enact federal legislation.美国国会是唯一有权颁布联邦法律的。
• For example,a country can enact laws and economic policies to attract foreign investment fairly quickly.例如一个国家可以很快颁布吸引外资的法令和经济政策。