They are the extreme bounds of the sun's course.

The reader must observe that the astronomical parts of this book are introduced by the Stoic as proofs of design and reason in the universe; and, notwithstanding the errors in his planetary system, his intent is well answered, because all he means is that the regular motions of the heavenly bodies, and their dependencies, are demonstrations of a divine mind.

The inference proposed to be drawn from his astronomical observations is as just as if his system was in every part unexceptionably right: the same may be said of his anatomical observations.
[166] In the zodiac.
[167] Ibid.
[168] These verses of Cicero are a translation from a Greek poem of Aratus, called the Phaenomena.
[169] The fixed stars.
[170] The arctic and antarctic poles.
[171] The two Arctoi are northern constellations.

Cynosura is what we call the Lesser Bear; Helice, the Greater Bear; in Latin, _Ursa Minor_ and _Ursa Major_.
[172] These stars in the Greater Bear are vulgarly called the "Seven Stars," or the "Northern Wain;" by the Latins, "Septentriones." [173] The Lesser Bear.
[174] The Greater Bear.
[175] Exactly agreeable to this and the following description of the Dragon is the same northern constellation described in the map by Flamsteed in his Atlas Coelestis; and all the figures here described by Aratus nearly agree with the maps of the same constellations in the Atlas Coelestis, though they are not all placed precisely alike.
[176] The tail of the Greater Bear.
[177] That is, in Macedon, where Aratus lived.
[178] The true interpretation of this passage is as follows: Here in Macedon, says Aratus, the head of the Dragon does not entirely immerge itself in the ocean, but only touches the superficies of it.

By _ortus_ and _obitus_ I doubt not but Cicero meant, agreeable to Aratus, those parts which arise to view, and those which are removed from sight.
[179] These are two northern constellations.