Comets Consist of the Milky Way

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. 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. And now, the circle of the zodiac dissolves this kind of matter because of the sun and the planets, and for this reason most comets are found outside the tropic circles. Again, no fringe appears round