Meteorology   

hitherto.

Let us recall our fundamental principle and then explain our

views. We have already laid down that the outermost part of what is

called the air is potentially fire and that therefore when the air

is dissolved by motion, there is separated off a kind of matter-and of

this matter we assert that comets consist. We must suppose that what

happens is the same as in the case of the comets when the matter

does not form independently but is formed by one of the fixed stars or

the planets. Then these stars appear to be fringed, because matter

of this kind follows their course. In the same way, a certain kind

of matter follows the sun, and we explain the halo as a reflection

from it when the air is of the right constitution. Now we must

assume that what happens in the case of the stars severally happens in

the case of the whole of the heavens and all the upper motion. For

it is natural to suppose that, if the motion of a single star

excites a flame, that of all the stars should have a similar result,

and especially in that region in which the stars are biggest and

most numerous and nearest to one another. Now the circle of the zodiac

dissolves this kind of matter because of the motion of the sun and the

planets, and for this reason most comets are found outside the

tropic circles. Again, no fringe appears round the sun or moon: for

they dissolve such matter too quickly to admit of its formation. But

this circle in which the milky way appears to our sight is the

greatest circle, and its position is such that it extends far

outside the tropic circles. Besides the region is full of the

biggest and brightest constellations and also of what called

'scattered' stars (you have only to look to see this clearly). So

for these reasons all this matter is continually and ceaselessly

collecting there. A proof of the theory is this: In the circle

itself the light is stronger in that half where the milky way is

divided, and in it the constellations are more numerous and closer

to one another than in the other half; which shows that the cause of