XII. Again the facts do not square. Comets and planets appear simultaneously. A conjunction is momentary, a Comet lasts six months sometimes. The planets do not pass much beyond the ecliptic, but Comets appear in every quarter of the sky. And there are other objections 284 XIII. Artemidorus thinks the firmament is solid and has openings for stars. Comets are casual planets, or formed by conjunctions of them. His account is a tissue of barefaced falsehoods 286 XIV. How would a solid firmament be supported? No feasible explanation can be offered. Besides, the number of stars is so great--and they may all be “wanderers” if an indefinite number is--that there must be innumerable conjunctions of them, _i.e._ Comets. But, as a matter of fact, Comets are rare 287 XV. Again the huge Comets of the times of Demetrius and Attalus would require scores of planetary conjunctions to form them 288 XVI. Ephorus, a mere chronicler, who takes this view, has nothing to support him. He tries, like others of his set, to embellish his work by narrating marvels. Why did he not tell us what the two stars were into which the Comet resolved itself, as he alleges it did? 289 XVII. Apollonius of Myndus holds the Comet to be a true star (planet) with an erratic course, visible only when it approaches the lower part of its orbit. Different colours of Comets 290 XVIII. But Comets do not wax and wane as they approach and recede like planets. Nor do their orbits lie within the ecliptic. Besides, we can see through a Comet but not through a true star (planet) 291 XIX. Zeno the Stoic thinks the light of converging stars gives the appearance of a longer star. Others hold modified forms of the same opinion or analogous views 291 XX. Most of the Stoics hold Comets to be evanescent, and attribute them to friction of the air. Various phenomena are analogous 292 XXI. Their methods of accounting for varieties of orbits in Comets 293 XXII. I do not agree with any School. Reasons 295 XXIII. Further arguments showing difference between fires and Comets 295 XXIV. There may be many stars in the universe whose paths have not been traced: Comets are such. No satisfactory explanation has been given of the mind, but its existence is not doubted 297