because it set before the Sun; on the second day it was seen imperfectly, for it set immediately after the Sun in the west; its brightness extended over a third part of the sky: it reached as far as the belt of Orion, and there ceased. Aristotle points out that a concourse of stars does not constitute a comet. The Egyptian astronomers, he says, report that conjunctions of planets, both with one another, and with fixed stars, occur. He himself had observed Jupiter, in the constellation Gemini, on two occasions, coming into conjunction with a star, and occulting it, but without assuming the appearance of a tail. Aristotle himself thinks that comets are in the nature of meteors, and that their range is in the region nearest the earth."^[1]

The greatest Greek author of antiquity, Homer, in the Iliad, says:—

[The helmet of Achilles] f) 8', aarT)p us airib.anirev "Iirirovpis Tpv<baeia, itepiaatiovro 8' tOeipai Xpvfffai, a? "U<patffTos "id <f>ov u/jupl 6a/j.fias.

Thus rendered by Pope:—

[The helmet of Achilles shone] " Like the red star, that from his flaming hair Shakes down diseases, pestilence, and war." (Iliad, Bk. xix, 11. 380-3.)

Pope has evidently borrowed from Milton, as below.

It is a somewhat remarkable fact that Ptolemy, so celebrated for his varied astronomical attainments, should nowhere have made any mention of comets, but seemingly that was because he regarded them as objects terrestrial, not celestial. On the other hand, Pliny appears to have paid much attention to them, if we may judge by the fact that he enumerates 12 varieties, each kind receiving its name from some physical peculiarity of the objects belonging to it.

Hevelius gave sketches of 11 of Pliny's 12 forms, and their titles as follows:—

Disci : disciformis = discs. Pithei : doliiformis erectus = like an upright cask.