Meteorology   

We have already laid down that there is one physical element which

makes up the system of the bodies that move in a circle, and besides

this four bodies owing their existence to the four principles, the

motion of these latter bodies being of two kinds: either from the

centre or to the centre. These four bodies are fire, air, water,

earth. Fire occupies the highest place among them all, earth the

lowest, and two elements correspond to these in their relation to

one another, air being nearest to fire, water to earth. The whole

world surrounding the earth, then, the affections of which are our

subject, is made up of these bodies. This world necessarily has a

certain continuity with the upper motions: consequently all its

power and order is derived from them. (For the originating principle

of all motion is the first cause. Besides, that clement is eternal and

its motion has no limit in space, but is always complete; whereas

all these other bodies have separate regions which limit one another.)

So we must treat fire and earth and the elements like them as the

material causes of the events in this world (meaning by material

what is subject and is affected), but must assign causality in the

sense of the originating principle of motion to the influence of the

eternally moving bodies.



3



Let us first recall our original principles and the distinctions

already drawn and then explain the 'milky way' and comets and the

other phenomena akin to these.

Fire, air, water, earth, we assert, originate from one another,

and each of them exists potentially in each, as all things do that can

be resolved into a common and ultimate substrate.

The first difficulty is raised by what is called the air. What are

we to take its nature to be in the world surrounding the earth? And