I would like to give the reader some idea of the textual and interpretive problems we have confronted in seeking to restore the doctrine of Hellenistic astrology to its original state.
The good news is that nearly all the primary Hellenistic sources in Greek and Latin have been edited in modern critical editions. The bad news is partly the condition in which the Hellenistic writings survive, and partly the manner in which they were originally composed.
For the first issue, let us take the two extreme cases. On the one hand, there is the received text of Ptolemy's Tetrabiblos, which has survived virtually intact in Greek. There is not all that much difference in the numerous surviving manuscripts. However, if we read Hephaistio's quotations from the Tetrabiblos in his own Apotelesmatics, which are often verbatim, we find numerous places where the two versions differ considerably, particularly in some of the more difficult procedural sections, where the correct reading makes all the difference as far as the details of astrological practice are concerned. A good instance of this occurs in Book II, chapter 23 of the Hephaistio text, dealing with the topic of friends and enemies.
On the other hand, there is the equally important work of Dorotheus, which was originally composed in Greek verse, then translated into an old Persian dialect, and from there into Arabic, whereupon we now have a modern critical edition of the Arabic text translated into English by David Pingree. The original Greek version survives only in fragments. Comparison of the Greek verse fragments with the English translation shows innumerable differences and even direct contradictions on the details of astrological practice and interpretation. Summaries of topical treatments of Dorotheus by Hephaistio cannot always be cross-referenced to anything found in the Arabic version. There are also passages that are clearly Arabian interpolations. We conclude that the portion surviving only in the Arabic translation must be used with great caution.
In between these two extremes we have the Anthology of Vettius Valens, which fortunately survives in Greek, but in a rather messy condition. The text is riddled with lacunae and occasional garbled passages, which have a habit of occurring at critical places. For instance, the sole passage dealing with secondary progressions in the whole of the Hellenistic corpus is found in this work, but degenerates into nonsense after a few sentences. Again, in another passage Valens has just correlated the basic "essences" of the planets with faculties of the soul, and is about to go on when the text breaks off. Passages such as this are absolutely maddening.
Next, let us turn to the manner in which these books were composed, starting with the work of Nechepso/Petosiris, the primary source text for all later Hellenistic astrology, which regrettably only survives in fragments quoted by later authors. Valens himself occasionally mentions how "enigmatical" or "mysterious" certain passages are in this work. Now, there is a central concept in Hellenistic astrology called the "Lot of Fortune," which is calculated as an arithmetical function of the Sun, Moon, and Ascendant. The question concerns whether the position of the Sun and Moon should be reversed in the algorithm depending on whether it is a day or night birth. Ptolemy calculates the lot the same way for both day and night births, whereas most other astrologers reverse it. Valens wrestles with this problem in the Anthology and actually quotes the passage in question--and it is indeed enigmatical. Now, this is the source text that all later astrologers were depending on, and they cannot agree on this crucially important concept.
Again, numerous astrological compositions, such as that of Dorotheus, were composed in Greek verse, using archaic words and word forms. It is easy to see how the requirements of versification could often lead to tricky or elliptical formulations of technical procedures that could easily be misinterpreted, and how the use of metaphor and other rhetorical tropes could also lead to serious ambiguity.
The treatise of Ptolemy is a marvel of architectonic literary composition, with gigantic sentences and clauses nested inside of clauses nested inside of clauses, all beautifully coordinated by those clever little logical connectives called "Greek particles," which sometimes serve as punctuation, sometimes give subtle verbal emphasis, and frequently tie all the hierarchical logic of the sentence together. These particles are often nearly untranslatable into English. This work was hard for even Greek literates to read. There is a paraphrase of it ascribed to Proclus, which is scarcely any shorter than the original, but is considerably "dumbed down," often at the expense of the original meaning.
Again we have Valens falling somewhere in between, alternating between exceedingly dry procedural exposition accompanied by pithy algorithmic statements, and lofty epistolary addresses to one Marcus, composed in an entangled run-on style the very opposite of Ptolemy's, with participial clauses following upon participial clauses, often having vague or shifting antecedent nouns. Unfortunately, it is in these difficult passages that Valens is most reflective and philosophical.
However, all of these writers have in common a certain compositional device that is a bit hard to notice at first. If we moderns have a number of parallel passages to write that may contain some repetition, or that are to be developed analogically in each instance, we are taught to set out the complete overall template with the first instance, and then refer back to it as necessary. It is basically the same principle as putting in ditto marks to avoid repeating something verbatim. Often the Hellenistic authors needed to compile interpretive text for all possible planetary combinations, as when they are delineating aspect combinations of planets. The basic meaning of the planetary combination may be varied almost ad infinitum by bringing in a third planet in various ways, and according to the different positions of the planetary pair in the natal chart. Whereas we would probably do a fairly complete treatment of the first planetary pair, and indicate that the same should be done for all other pairs, perhaps actually writing out any variations that might seem exceptional in any way, the Hellenistic astrologers take the basic delineation template with all its variations and distribute it throughout the entire set of planetary pairs. As a consequence, you cannot grasp the complete template unless you reassemble its parts from the different planetary pairs. I cannot say at the present time whether this was simply a literary device or a means of deliberately withholding crucial details of the doctrine from the uninitiated or unworthy—a concern often voiced by astrologers such as Vettius Valens.
To be candid, we simply do not know the full extent to which the Hellenistic authors such as Valens, Dorotheus, and even Ptolemy may have sought to encrypt their doctrine, or all the devices of esoteric writing they might have employed for this purpose. But we must take it as a serious possibility that they did so. We must likewise consider the possibility that these Hellenistic authors, who were already three hundred years removed from their own source texts, were no longer fully in possession of the original doctrine themselves.
In view of all this, the prospect of restoring Hellenistic astrology in any meaningful way would be almost hopeless were not for one thing — the technical Greek vocabulary of the Hellenistic astrologers. This, I would argue, by itself preserves the entire doctrine nearly intact. However, this terminology is initially quite baffling. One cannot simply look up the words in a Greek lexicon and translate them accordingly. The lexical entries are only as good as the understanding of the men who compiled them. Since no one has ever taken the trouble to really get to the root of Hellenistic astrological doctrine, the definitions found in the lexicons are rarely helpful in truly understanding the astrological concepts.
Thus, if we look up the Greek word epimarturia , one of the common Greek words for a planetary configuration today called an “aspect,” we find the definition “supporting by aspect” under the heading of astrological usages. However, the root meaning of the Greek word is “testimony.” This implies that the Greek word is not simply chosen to single out and identify without ambiguity an astronomical arrangement of planets (as would be the ideal of modern technical language). Instead, the word is chosen to convey a thought about this planetary arrangement, to suggest its interpretation. If we simply translated it as “aspect” or “supporting by aspect,” we would leave this thought behind entirely. So we must ask ourselves why the Hellenistic astrologers chose such a strange word to describe this kind of planetary combination before we can translate it properly. Most of the technical terms in Hellenistic astrology pose similar challenges.