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Bill Thayer

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Caelum Antiquum:
Ancient Astronomy and Astrology
Resources on LacusCurtius

[image ALT: A woodcut of the head and shoulders of a man in late middle age. He is bearded and moustached and wears a slashed silk blouse and an elaborate flat hat, and holds a paper in his hand. It is an imaginative Renaissance 'portrait' of the Greek astronomer and mathematician Ptolemy.]

[ complete English translation ]

For a thousand years, Ptolemy's Tetrabiblos was one of the most popular technical manuals in the world, that taught the rudiments of casting an astrological chart to many generations of practitioners.

(His greater work on the heavens — the Almagest — is not onsite yet.)

[image ALT: A drawing of the head and shoulders of a ram, although softer and fuzzier than that animal is usually depicted; its face is marked by several stars. It is a detail of the constellation Aries from a 17c star atlas, the Harmonia macrocosmica of Andreas Cellarius, and serves as an icon for Allen's Star Names on my site.]

[ 12/28/07: complete: 486 pages of print ]

Allen's Star Names is a monumental 20c compendium on the origins of star names: Greek and Roman, but also Arabic and Babylonian and more exotic languages still; Dante and our English poets, and the heroic era of scientific astronomy, and here and there, other loosely related information that appealed to him. Flawed, superseded, but occasionally fascinating reading.

Onsite link

[ complete Latin text
(linked in the header to an English translation) ]

Book II of Pliny's Natural History: cosmology, the sun, moon and planets, comets and meteors; planetary motions and orbits; eclipses; the effects of the planets on weather and tides; the relationship between astronomy and geography.

Onsite link

[ complete Latin text and French translation ]

Censorinus' de Die natali is a major source of Roman calendrical information; but also includes material on the zodiac and gestation, the Pythagorean musical organization of the heavens, the climacterics, the Etruscan "centuries", cosmological cycles, and sundials.

[image ALT: A group of Egyptian hieroglyphs, used here as an icon for Plutarch's Isis and Osiris.]

[ complete English translation ]

Plutarch's Isis and Osiris is a cerebral mix of cosmology and philosophy, in which the sun, the moon and their influences figure prominently.

[image ALT: A full moon, used here as an icon for Plutarch's De Facie.]

[ complete English translation ]

Plutarch's On the Face in the Moon is another even more deadly cerebral mix of cosmology and philosophy, which will keep the enquiring mind busy for a very long time.

[image ALT: an onsite link.]

[ 8/24/07: in progress ]

Smith's Dictionary of Greek and Roman Antiquities includes a few articles on the ancient heavens and related material. The main one, Astronomia, runs to 40,000 words — and I haven't got around to putting it online. The following articles, however, are available:

Astrologia Clima Horologium Polus

Onsite link

The 1911 Encyclopaedia Britannica also has a number of articles on astronomy and astrology, often written by top authorities. I don't expect to put many of them up, but they're occasionally cited on other pages of mine, so it'll prove useful to transcribe some of them. For now, just one: Zodiac.

Onsite link

The Roman architect Vitruvius surprisingly states that architecture consists of three branches: the construction of buildings, of engines of war — and of sundials; and so he covers sundials, along with much astronomy, in Book IX of his de Architectura. The diligent student could also do worse than read the rest of Vitruvius as well, in which astronomy or the influence of the luminaries appears, in one way or another, in every book except III and IV.

Onsite link

Cicero, in the de Divinatione, spends a fair amount of ink on astronomy and astrology: he distinguishes them and judges the latter to be rank superstition. The most relevant section is Book II.42.87‑47.99, but the topic crops up frequently thruout the work.

Onsite link

Continuing in the sceptical vein, Gellius reports a lecture of the philosopher Favorinus, who says astrology is bunk and explains why: Attic Nights, XIV.1 (for now, in Latin only).

Onsite link

Midway between belief in astrology and total scepticism, we have the agnosticism of a great historian, and an interesting incident, likely enough to be true that he reported it: Tacitus, Annals, VI.20‑22.

Onsite link

The 6c encyclopedist Isidore has something to say on astronomy; about half a Book's worth: Orig. III, chs. 24‑end.

Onsite link

The historian Ammian devotes a rather long passage of Book XX of his Roman History to solar eclipses. He's rather shaky on the whole concept. . . .

Onsite link

And finally, very brief, but fascinating: the Late Antique poet Claudian wrote verses on Archimedes' Sphere that give us a tantalizing glimpse into the mechanics of what seems to have been a rather complex orrery of sorts.

Notes and Studies:

Astronomy and Astrology in India and Iran although highly technical and not as wide-ranging as the title suggests, is of interest: the author maintains that Babylonian astronomy and astrology were mediated to India not thru Iran but thru the Greeks.

There was a rather confused Roman tradition connecting Romulus, the founder of Rome, with solar eclipses: the three very different main versions are found in Dio and two works by Plutarch. I've tried to untangle it all, by way of footnotes to each text. These notes are all cross-linked, so you may as well start with the one in Dio.

In the English-speaking world, the eclipse-dependent date of the battle of Pydna is usually given as June 21, 168 B.C.; in Europe, agreement tends to be in favor of September 3, 172 B.C. This note of mine, squirreled away in Plutarch's Life of Aemilius, is long enough to be a journal article — I suppose I should work it up into a separate page — and explains why I side with the Europeans.

An exchange of views on the chronology of the eclipse of Pericles may be found in The Observatory, Vol. VII, with a bit more added in by me; and a brief article in Classical Quarterly, Vol. XIII.

Manilius, Augustus, Tiberius, Capricorn and Libra, an article by A. E. Housman, exploring the horoscopes of Augustus and Tiberius and impacting the dating of Book IV of Manilius. The problematic Capricorn-sign of Augustus is resolved not as the sign under which he was conceived, but his moon sign.

The horoscope of Nero, a footnote to his biography by Suetonius.

The Roman Farmer and the Moon (TAPA 49:67‑82), a sourcebook: Pliny, Columella, Varro, and others on the agricultural properties of the moon: waxing, waning, or invisible.

[image ALT: A round stone medallion carved with a star. It is a detail from the façade of the cathedral of Orvieto (central Italy), and serves as an icon for this subsite.]

The icon I use to indicate this subsite is a detail from my photograph of the Adoration of the Magi by Maitani on the façade of the cathedral of Orvieto. This may seem an odd choice, but it's the best website identifier I could come up with: the event occurred in Antiquity (and has given rise to a vast literature firmly seated in the interface between astronomy, astrology, and ancient history), the protagonists seem to have been Babylonian astrologer/astronomers, the sculptor consciously broke with medieval tradition to work in something very much like the style of Trajan's Column, and the marble itself came from the ruins of the Mausoleum of Augustus.


de Architectura, I.3.1.

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Site updated: 16 Dec 17