Book v chapter 2

It is the same also with hearing and smell; to hear and smell accurately¹ mean in one sense to perceive as precisely² as possible all the distinctions of the objects of perception, in another sense to hear and smell far off. As with sight, so here the sense-organ is the cause of judging well the distinctions, if both that organ itself and the membrane³ round it be pure. For the passages of all the sense-organs, as has been said in the treatise⁴ on sensation, run to the heart, or to its analogue⁵ in creatures that have no heart. The passage of the hearing, then, since this sense-organ is of air, ends at the place where the innate⁶ spiritus causes in some animals the pulsation⁷ of the heart and in others respiration⁸; wherefore also it is that we are able to understand what is said and repeat what we have heard, for as was the movement which entered through the sense-organ, such again is the movement which is caused by means of the voice, being as it were of one and the same stamp, so that a man can say what he has heard. And we hear less well during a yawn or expiration⁹ than during inspiration, because the starting-point of the sense-organ of hearing is set upon the part concerned with breathing and is shaken and moved as the organ moves the breath, for while setting the breath in motion it is moved itself. The same thing happens in wet weather or a damp atmosphere. . . . And the ears seemed to be filled with air because their starting-point is near the region of breathing.

Accuracy then in judging the differences of sounds and smells depends on the purity of the sense-organ and of the membrane lying upon its surface, for then all the movements become clear in such cases, as in the case of sight. Perception and non-perception at a distance also depend on the same things with hearing and smell as with sight. For those animals can perceive at a distance which have channels, so to say, running through the parts concerned and projecting far in front of the sense-organs. Therefore all animals whose nostrils¹⁰ are long, as the Laconian hounds, are keen-scented, for the sense-organ being above them, the movements from a distance are not dissipated but go straight to the mark, just as the movements which cause sight do with those who shadow the eyes with the hand.

Similar is the case of animals whose ears are long and project far like the eaves of a house, as in some quadrupeds, with the internal spiral passage long; these also catch the movement from afar and pass it on to the sense-organ.

In respect of sense-perception at a distance, man is, one may say, the worst of all animals in proportion to his size, but in respect of judging the differences of quality in the objects he is the best of all. The reason is that the sense-organ in man is pure and least earthy and material, and he is by nature the thinnest-skinned of all animals for his size.

The workmanship of Nature is admirable also in the seal, for though a viviparous quadruped it has no ears but only passages for hearing. This is because its life is passed in the water; now the ear is a part added to the passages to preserve the movement of the air at a distance; therefore an ear is no use to it but would even bring about the contrary result by receiving a mass of water into itself.

We have thus spoken of sight, hearing, and smell.

1 accurately   

adv.准确地，精确地

参考例句：

• It is hard to hit the ball accurately.准确地击中球很难。
• Now scientists can forecast the weather accurately.现在科学家们能准确地预报天气。

2 precisely   

adv.恰好，正好，精确地，细致地

参考例句：

• It's precisely that sort of slick sales-talk that I mistrust.我不相信的正是那种油腔滑调的推销宣传。
• The man adjusted very precisely.那个人调得很准。

3 membrane   

n.薄膜，膜皮，羊皮纸

参考例句：

• A vibrating membrane in the ear helps to convey sounds to the brain.耳膜的振动帮助声音传送到大脑。
• A plastic membrane serves as selective diffusion barrier.一层塑料薄膜起着选择性渗透屏障的作用。

4 treatise   

n.专著；(专题)论文

参考例句：

• The doctor wrote a treatise on alcoholism.那位医生写了一篇关于酗酒问题的论文。
• This is not a treatise on statistical theory.这不是一篇有关统计理论的论文。

5 analogue   

n.类似物；同源语

参考例句：

• The gill of a fish is the analogue of the lung of a cat.鱼的鳃和猫的肺是类似物。
• But aside from that analogue standby,the phone, videoconferencing is their favorite means of communication.除了备用的相似物电话，可视对话是他们最喜欢的沟通手段。

6 innate   

adj.天生的，固有的，天赋的

参考例句：

• You obviously have an innate talent for music.你显然有天生的音乐才能。
• Correct ideas are not innate in the mind.人的正确思想不是自己头脑中固有的。

7 pulsation   

n.脉搏，悸动，脉动；搏动性

参考例句：

• At low frequencies, such as 10 per sec., pulsation is sensed rather than vibration. 在低频率（譬如每秒十次）时，所感觉到的是脉冲而非振动。 来自辞典例句
• If the roller pulsation, the pressure on paper as cause misregister. 如果滚子径向跳不静，则差纸的不张辛有不小有小，致使套印禁绝。 来自互联网

8 respiration   

n.呼吸作用；一次呼吸；植物光合作用

参考例句：

• They tried artificial respiration but it was of no avail.他们试做人工呼吸，可是无效。
• They made frequent checks on his respiration,pulse and blood.他们经常检查他的呼吸、脉搏和血液。

9 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。

10 nostrils   

鼻孔( nostril的名词复数 )

参考例句：

• Her nostrils flared with anger. 她气得两个鼻孔都鼓了起来。
• The horse dilated its nostrils. 马张大鼻孔。