Chapter 7

We have next to speak of the stars, as they are called, of their composition, shape, and movements. It would be most natural and consequent upon what has been said that each of the stars should be composed of that substance in which their path lies, since, as we said, there is an element whose natural movement is circular. In so saying we are only following the same line of thought as those who say that the stars are fiery¹ because they believe the upper body to be fire, the presumption² being that a thing is composed of the same stuff as that in which it is situated³. The warmth and light which proceed from them are caused by the friction⁴ set up in the air by their motion. Movement tends to create fire in wood, stone, and iron; and with even more reason should it have that effect on air, a substance which is closer to fire than these. An example is that of missiles, which as they move are themselves fired so strongly that leaden balls are melted; and if they are fired the surrounding air must be similarly affected⁵. Now while the missiles are heated by reason of their motion in air, which is turned into fire by the agitation⁶ produced by their movement, the upper bodies are carried on a moving sphere, so that, though they are not themselves fired, yet the air underneath⁷ the sphere of the revolving⁸ body is necessarily heated by its motion, and particularly in that part where the sun is attached to it. Hence warmth increases as the sun gets nearer or higher or overhead. Of the fact, then, that the stars are neither fiery nor move in fire, enough has been said.

1 fiery   

adj.燃烧着的，火红的；暴躁的；激烈的

参考例句：

• She has fiery red hair.她有一头火红的头发。
• His fiery speech agitated the crowd.他热情洋溢的讲话激动了群众。

2 presumption   

n.推测，可能性，冒昧，放肆，[法律]推定

参考例句：

• Please pardon my presumption in writing to you.请原谅我很冒昧地写信给你。
• I don't think that's a false presumption.我认为那并不是错误的推测。

3 situated   

adj.坐落在...的，处于某种境地的

参考例句：

• The village is situated at the margin of a forest.村子位于森林的边缘。
• She is awkwardly situated.她的处境困难。

4 friction   

n.摩擦，摩擦力

参考例句：

• When Joan returned to work,the friction between them increased.琼回来工作后，他们之间的摩擦加剧了。
• Friction acts on moving bodies and brings them to a stop.摩擦力作用于运动着的物体，并使其停止。

5 affected   

adj.不自然的，假装的

参考例句：

• She showed an affected interest in our subject.她假装对我们的课题感到兴趣。
• His manners are affected.他的态度不自然。

6 agitation   

n.搅动；搅拌；鼓动，煽动

参考例句：

• Small shopkeepers carried on a long agitation against the big department stores.小店主们长期以来一直在煽动人们反对大型百货商店。
• These materials require constant agitation to keep them in suspension.这些药剂要经常搅动以保持悬浮状态。

7 underneath   

adj.在...下面，在...底下；adv.在下面

参考例句：

• Working underneath the car is always a messy job.在汽车底下工作是件脏活。
• She wore a coat with a dress underneath.她穿着一件大衣，里面套着一条连衣裙。

8 revolving   

adj.旋转的，轮转式的；循环的v.（使）旋转( revolve的现在分词 )；细想

参考例句：

• The theatre has a revolving stage. 剧院有一个旋转舞台。
• The company became a revolving-door workplace. 这家公司成了工作的中转站。