Chapter 3

In consequence of what has been said, in part by way of assumption and in part by way of proof, it is clear that not every body either possesses lightness or heaviness. As a preliminary we must explain in what sense we are using the words ‘heavy’ and ‘light’, sufficiently¹, at least, for our present purpose: we can examine the terms more closely later, when we come to consider their essential nature. Let us then apply the term ‘heavy’ to that which naturally moves towards the centre, and ‘light’ to that which moves naturally away from the centre. The heaviest thing will be that which sinks to the bottom of all things that move downward, and the lightest that which rises to the surface of everything that moves upward. Now, necessarily, everything which moves either up or down possesses lightness or heaviness or both-but not both relatively² to the same thing: for things are heavy and light relatively to one another; air, for instance, is light relatively to water, and water light relatively to earth. The body, then, which moves in a circle cannot possibly possess either heaviness or lightness. For neither naturally nor unnaturally³ can it move either towards or away from the centre. Movement in a straight line certainly does not belong to it naturally, since one sort of movement is, as we saw, appropriate to each simple body, and so we should be compelled to identify it with one of the bodies which move in this way. Suppose, then, that the movement is unnatural⁴. In that case, if it is the downward movement which is unnatural, the upward movement will be natural; and if it is the upward which is unnatural, the downward will be natural. For we decided⁵ that of contrary movements, if the one is unnatural to anything, the other will be natural to it. But since the natural movement of the whole and of its part of earth, for instance, as a whole and of a small clod-have one and the same direction, it results, in the first place, that this body can possess no lightness or heaviness at all (for that would mean that it could move by its own nature either from or towards the centre, which, as we know, is impossible); and, secondly⁶, that it cannot possibly move in the way of locomotion⁷ by being forced violently aside in an upward or downward direction. For neither naturally nor unnaturally can it move with any other motion but its own, either itself or any part of it, since the reasoning which applies to the whole applies also to the part.

It is equally reasonable to assume that this body will be ungenerated and indestructible and exempt⁸ from increase and alteration⁹, since everything that comes to be comes into being from its contrary and in some substrate, and passes away likewise in a substrate by the action of the contrary into the contrary, as we explained in our opening discussions. Now the motions of contraries are contrary. If then this body can have no contrary, because there can be no contrary motion to the circular, nature seems justly to have exempted¹⁰ from contraries the body which was to be ungenerated and indestructible. For it is in contraries that generation and decay subsist¹¹. Again, that which is subject to increase increases upon contact with a kindred body, which is resolved into its matter. But there is nothing out of which this body can have been generated. And if it is exempt from increase and diminution¹², the same reasoning leads us to suppose that it is also unalterable. For alteration is movement in respect of quality; and qualitative¹³ states and dispositions¹⁴, such as health and disease, do not come into being without changes of properties. But all natural bodies which change their properties we see to be subject without exception to increase and diminution. This is the case, for instance, with the bodies of animals and their parts and with vegetable bodies, and similarly also with those of the elements. And so, if the body which moves with a circular motion cannot admit of increase or diminution, it is reasonable to suppose that it is also unalterable.

The reasons why the primary body is eternal and not subject to increase or diminution, but unaging and unalterable and unmodified, will be clear from what has been said to any one who believes in our assumptions. Our theory seems to confirm experience and to be confirmed by it. For all men have some conception of the nature of the gods, and all who believe in the existence of gods at all, whether barbarian¹⁵ or Greek, agree in allotting¹⁶ the highest place to the deity¹⁷, surely because they suppose that immortal¹⁸ is linked with immortal and regard any other supposition as inconceivable. If then there is, as there certainly is, anything divine, what we have just said about the primary bodily substance was well said. The mere¹⁹ evidence of the senses is enough to convince us of this, at least with human certainty. For in the whole range of time past, so far as our inherited records reach, no change appears to have taken place either in the whole scheme of the outermost²⁰ heaven or in any of its proper parts. The common name, too, which has been handed down from our distant ancestors even to our own day, seems to show that they conceived of it in the fashion which we have been expressing. The same ideas, one must believe, recur²¹ in men’s minds not once or twice but again and again. And so, implying that the primary body is something else beyond earth, fire, air, and water, they gave the highest place a name of its own, aither, derived²² from the fact that it ‘runs always’ for an eternity²³ of time. Anaxagoras, however, scandalously misuses²⁴ this name, taking aither as equivalent to fire.

It is also clear from what has been said why the number of what we call simple bodies cannot be greater than it is. The motion of a simple body must itself be simple, and we assert that there are only these two simple motions, the circular and the straight, the latter being subdivided²⁵ into motion away from and motion towards the centre.

1 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。

2 relatively   

adv.比较...地，相对地

参考例句：

• The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
• The operation was relatively painless.手术相对来说不痛。

3 unnaturally   

adv.违反习俗地；不自然地；勉强地；不近人情地

参考例句：

• Her voice sounded unnaturally loud. 她的嗓音很响亮，但是有点反常。 来自《简明英汉词典》
• Her eyes were unnaturally bright. 她的眼睛亮得不自然。 来自《简明英汉词典》

4 unnatural   

adj.不自然的；反常的

参考例句：

• Did her behaviour seem unnatural in any way?她有任何反常表现吗？
• She has an unnatural smile on her face.她脸上挂着做作的微笑。

5 decided   

adj.决定了的，坚决的；明显的，明确的

参考例句：

• This gave them a decided advantage over their opponents.这使他们比对手具有明显的优势。
• There is a decided difference between British and Chinese way of greeting.英国人和中国人打招呼的方式有很明显的区别。

6 secondly   

adv.第二，其次

参考例句：

• Secondly,use your own head and present your point of view.第二，动脑筋提出自己的见解。
• Secondly it is necessary to define the applied load.其次，需要确定所作用的载荷。

7 locomotion   

n.运动，移动

参考例句：

• By land,air or sea,birds are masters of locomotion.无论是通过陆地，飞越空中还是穿过海洋，鸟应算是运动能手了。
• Food sources also elicit oriented locomotion and recognition behavior patterns in most insects.食物源也引诱大多数昆虫定向迁移和识别行为。

8 exempt   

adj.免除的；v.使免除；n.免税者，被免除义务者

参考例句：

• These goods are exempt from customs duties.这些货物免征关税。
• He is exempt from punishment about this thing.关于此事对他已免于处分。

9 alteration   

n.变更，改变；蚀变

参考例句：

• The shirt needs alteration.这件衬衣需要改一改。
• He easily perceived there was an alteration in my countenance.他立刻看出我的脸色和往常有些不同。

10 exempted   

使免除[豁免]( exempt的过去式和过去分词 )

参考例句：

• His bad eyesight exempted him from military service. 他因视力不好而免服兵役。
• Her illness exempted her from the examination. 她因病而免试。

11 subsist   

vi.生存，存在，供养

参考例句：

• We are unable to subsist without air and water.没有空气和水我们就活不下去。
• He could subsist on bark and grass roots in the isolated island.在荒岛上他只能靠树皮和草根维持生命。

12 diminution   

n.减少；变小

参考例句：

• They hope for a small diminution in taxes.他们希望捐税能稍有减少。
• He experienced no diminution of his physical strength.他并未感觉体力衰落。

13 qualitative   

adj.性质上的，质的，定性的

参考例句：

• There are qualitative differences in the way children and adults think.孩子和成年人的思维方式有质的不同。
• Arms races have a quantitative and a qualitative aspects.军备竞赛具有数量和质量两个方面。

14 dispositions   

安排( disposition的名词复数 )； 倾向； （财产、金钱的）处置； 气质

参考例句：

• We got out some information about the enemy's dispositions from the captured enemy officer. 我们从捕获的敌军官那里问出一些有关敌军部署的情况。
• Elasticity, solubility, inflammability are paradigm cases of dispositions in natural objects. 伸缩性、可缩性、易燃性是天然物体倾向性的范例。

15 barbarian   

n.野蛮人；adj.野蛮(人)的；未开化的

参考例句：

• There is a barbarian tribe living in this forest.有一个原始部落居住在这个林区。
• The walled city was attacked by barbarian hordes.那座有城墙的城市遭到野蛮部落的袭击。

16 allotting   

分配，拨给，摊派( allot的现在分词 )

参考例句：

17 deity   

n.神，神性；被奉若神明的人(或物)

参考例句：

• Many animals were seen as the manifestation of a deity.许多动物被看作神的化身。
• The deity was hidden in the deepest recesses of the temple.神藏在庙宇壁龛的最深处。

18 immortal   

adj.不朽的；永生的，不死的；神的

参考例句：

• The wild cocoa tree is effectively immortal.野生可可树实际上是不会死的。
• The heroes of the people are immortal!人民英雄永垂不朽！

19 mere   

adj.纯粹的；仅仅，只不过

参考例句：

• That is a mere repetition of what you said before.那不过是重复了你以前讲的话。
• It's a mere waste of time waiting any longer.再等下去纯粹是浪费时间。

20 outermost   

adj.最外面的，远离中心的

参考例句：

• He fired and hit the outermost ring of the target.他开枪射中了靶子的最外一环。
• The outermost electron is shielded from the nucleus.原子核对最外层电子的作用受到屏蔽。

21 recur   

vi.复发，重现，再发生

参考例句：

• Economic crises recur periodically.经济危机周期性地发生。
• Of course,many problems recur at various periods.当然，有许多问题会在不同的时期反复提出。

22 derived   

vi.起源；由来；衍生；导出v.得到( derive的过去式和过去分词 )；（从…中）得到获得；源于；（从…中）提取

参考例句：

• Many English words are derived from Latin and Greek. 英语很多词源出于拉丁文和希腊文。 来自《简明英汉词典》
• He derived his enthusiasm for literature from his father. 他对文学的爱好是受他父亲的影响。 来自《简明英汉词典》

23 eternity   

n.不朽，来世；永恒，无穷

参考例句：

• The dull play seemed to last an eternity.这场乏味的剧似乎演个没完没了。
• Finally,Ying Tai and Shan Bo could be together for all of eternity.英台和山伯终能双宿双飞，永世相随。

24 misuses   

n.用错，滥用( misuse的名词复数 )；误用者v.使用…不当( misuse的第三人称单数 )；把…派作不正当的用途；虐待；滥用

参考例句：

• He misuses his horses by giving them loads that are too heavy. 他给它们过重的负荷来虐待他的马。 来自互联网
• He often misuses his authority to tyrannize his underlings. 他常用手中的职权凌轹下属。 来自互联网

25 subdivided   

再分，细分( subdivide的过去式和过去分词 )

参考例句：

• The compound was subdivided into four living areas. 那个区域被划分成4个居住小区。
• This part of geologic calendar has not been satisfactorily subdivided. 这部分地质年代表还没有令人满意地再细分出来。