An introduction to HOROI Project

Note (2022/10/11): This introduction is to be revised soon.

Astrological manuscripts

Astrological texts written in Greek are occasionally found in original documents such as papyri and ostraca, which are published and typically translated in scholarly papers and series, but most often in Byzantine manuscripts. The earliest extant codices were copied in the ninth century CE, and therefore no original autographs of Hellenistic astrologers have survived, only copies of copies of their works. For example, we can find Vettius Valens’s Anthologies, the original of which was composed in the late second century CE, only in four primary manuscripts and their copies, none of which contain the whole text and are older than the late thirteenth century.

Manuscript transmission

A general feature of the manuscript transmission of not only astrological texts but any literary genre was that during the course of copying, alterations would be introduced in the texts. These changes would include losses and various errors, most of which are hardly inevitable while copying, as well as deliberate alterations such as omissions, abbreviations, transpositions, rewrites, or additions on the margin or in the text itself. Astrological texts were particularly exposed to these sorts of alterations since they mostly served as technical manuals that would often be accommodated to the expectations of their readers. These changes, however, are hard or even impossible to trace. To give an example: although Valens is strongly suspected to have been born on February 8, 120 since a birth horoscope corresponding to this date is used as an example throughout the Anthologies, the last entry in his catalog of emperors (Anthologies 1.17) refers to Philip the Arab, who reigned from 244 to 249; therefore his work was edited sometime in the third century or later. Furthermore, there are some notes, originally marginal, that now are incorporated in the main text, and it is also likely that the Anthologies does not cover all the surviving writings of Valens.


A distinctive feature of astrological manuscripts is that while they sometimes contain entire works of well-known authors like Claudius Ptolemy, even more often, their scribes copied only selected chapters. These selections were typically incorporated into vast anthologies, some containing hundreds of chapters. The contents of these anthologies vary from manuscript to manuscript, but usually, they preserve many fragments from otherwise lost works of Hellenistic authors, matters translated from Arabic astrologers, or compendia assembled by Byzantine scholars. Still, most of the texts included in them are ‘adespota,’ ascribed to no author.

For instance, a manuscript produced by the Byzantine scholar Isaac Argyrus between 1373 and 1381 (now manuscript “Pluteus 28.13” kept in Biblioteca Medicea Laurenziana in Florence, Italy), besides a political horoscope cast and a few astronomical treatises composed by Argyrus himself, contains a lengthy compendium titled [Excerpts] from the Outcomes of Hephaestio of Thebes and Other Men of Old. Argyrus compiled and edited it from Hephaestio, Julianus of Laodicea, a certain Syrus, “Hermes Trismegistus,” Imbrasius of Ephesus (the real author behind Galen, to whom the short work is attributed here), Pancharius, Stephanus of Alexandria, and many more unnoticed authors, one of whom appears to be Theophilus of Edessa.

Critical editions and English translations

Beginning with the 1851 edition of the astrological poems of “Manetho” and Maximus of Ephesus by Hermann Köchly, scholars have edited many Hellenistic and Byzantine astrological texts, chiefly major works like Valens’s Anthologies, in so-called ‘critical editions.’ These editions are produced by comparing the available manuscript witnesses with the aim of eliminating the errors and constituting the best text as much as it is possible by using the sources and the methodology of textual criticism. The qualities of these editions, however, differ significantly: more recent editions, such as the 1975–76 edition of Hephaestio by David Pingree, are usually more reliable since they take the different versions into consideration and, unlike the older editions, do not attempt to combine different texts into one “original” that may well never have existed in that form.

Nevertheless, many fragments of known authors and anonymous texts have never been edited, apart from several dozens of shorter and longer texts that were published by the editors of the famous Catalogus Codicum Astrologorum Graecorum (“The Catalog of the Codices of Greek Astrologers”), which is otherwise a nearly comprehensive catalog of Greek astrological manuscripts. As such, only about one-third of Argyrus’s From the Outcomes has been published and much less translated to English, even though Argyrus’s codex is only one of the hundreds of extant manuscripts.

Making critical editions requires a considerable amount of time and human effort. To give an example, due to its extremely complicated textual history, as of 2022, the compendium attributed to Rhetorius of Egypt has not been published despite the preparations having begun before 1977. Assuming the current development level of technology that could accelerate the publication of critical editions and the volume of the editions published in the last 170+ years, several centuries would still need to pass before every astrological text is found in critical editions. Translations, however, can be produced within a considerably shorter time, since even a single but fairly reliable manuscript witness is sufficient for a preliminary translation.

Yet, except for Eduardo Gramaglia’s 2017 translation of the astrological works of Theophilus, which was partly based on unedited manuscript sources, all the English translations produced so far have been made exclusively from critical editions — even though there remain quite a few texts already edited but as yet untranslated. If the hundreds of texts never edited and possibly just cursorily seen by the researchers that cataloged them are also taken into consideration, it is safe to state that the significant part of the astrological texts is still undiscovered.

The HOROI Project translation plan

The primary goal of HOROI Project is to give a remedy to this deficiency by creating a library of accessible English translations of the astrological texts originally written in or later translated to Greek, primarily those that have not been translated yet. It will encompass the period roughly between 150 BCE and 1450 CE, and not only texts of Hellenistic and Byzantine but also Indian, Middle Persian, and Arabic astrology will be covered inasmuch as they were translated to Greek. To preserve the comprehensive character of the project, I occasionally provide translations from Latin and Arabic as well.

What will be covered?

Complete or nearly complete works of major authors

For example, the untranslated chapters from “Rhetorius”, supplementing James H. Holden’s 2009 translation; a complete work on interrogations by Māshāʾallāh, otherwise lost in Arabic and apparently never translated to Latin; and the voluminous Byzantine compendium attributed to the fictional “Achmet the Persian”, Introduction and Foundation to Astrology will be translated. I also provide re-translations of major texts that have been previously translated from imperfect editions, such as Paulus of Alexandria’s Introduction to Astrology.

Excerpts, fragments, and testimonies of minor authors

What remains from Nechepsos and Petosiris, Teucer of Babylon, Julianus of Laodicea, Buzurjmihr, Rashīq ibn ʿAbdallāh al-Ḥāsib, Eleutherius of Gabala, and many others will be translated.


Anonymous works and isolated chapters found in manuscripts will be included among the translations. Beyond manuscript sources, relevant texts found on papyri and ostraca will also be translated.

Testimonies of outsiders

I will translate important testimonies of non-astrological authors and works that can shed light on the different aspects of astrology.


Although many case horoscopes were collected in publications like Greek Horoscopes by Otto Neugebauer and Henry Bartlett van Hoesen, several ones have not been translated or even published. These include, for example, the horoscopes of the city of Constantinople, the nativity of the vizier ʿAlī ibn ʿĪsā (born August 11, 859, died August 1, 946) analyzed by ʿAlī ibn Isḥāq al-Yahūdī, the nativity of the Byzantine emperor Constantine VII Porphyrogenitus (born September 3, 905, died November 15, 959), and other horoscopes illustrating the different branches of astrology. I will also provide new, improved translations of already translated horoscopes, such as the inceptions of the emperor Zeno’s Anonymous.

Translation conventions

Previous translations of Greek astrological texts are marked by the confessed or implicitly employed approach of their translators. As a result, those done by Robert Schmidt are notably literal, which often results in hardly comprehensible sentences, whereas Holden frequently employed technical terms that originate from medieval Latin translations of Arabic texts and as a result, often fail to convey the metaphoric subtleties of the Greek original. I decided to try and find the middle way and produce translations faithful to the original but still comprehensible. As for the terms, I use mostly literal translations of the Greek words instead of the Latinate modern equivalents, but do not insist on finding the optimal English rendering when it seems impossible. Therefore, I write ‘place’ with Schmidt and others for Holden’s ‘house’, and ‘sign’ with Holden and others for a simple transliteration or ‘image’, Schmidt’s ultimate choice.

To make the translations more accessible, I often give explanatory additions in (round brackets), or when an interpretation is implicitly signaled by the syntax, without indication. When in order to give a meaningful translation, I need to deviate from the Greek significantly, a more literal translation is added as a footnote. The emendations employed are also explained in the footnotes.

Occasionally, words or sentences lost in the texts can be also detected. If restoration is possible, I put the missing part in [square brackets]; if not, the sign [***] used. Irreparably corrupt passages are †daggered†, although in footnotes, I may provide a tentative reconstruction. Sentences that are judged to be insertions in the text are put in {curly bracket}.

The texts translated are usually extant in more than one manuscript witnesses, which are never entirely identical. I do not record all the differences, but I give the important variant readings in footnotes. In case of major differences, a whole parallel translation is provided. When applicable, the various recensions are treated in the same way, depending on whether the differences are significant enough to provide parallel texts.

Footnotes are also used to resolve references, add bibliographical information, provide interpretations, or a brief commentary.


I constantly revise the translations both to facilitate a better understanding and to incorporate the testimonies of the newly examined manuscript witnesses. Also, to bring forward translations as early as possible, the first versions are provided in full and ready translations but with minimal introduction and explanatory notes.


The translations are copyrighted unless they are published as freely distributable open-access texts under Creative Commons BY-NC-SA license. Please help to keep HOROI Project alive by not pirating my translations.

Derived translations

If you would like to use HOROI Project translations as a basis for re-translations to other languages, please contact me via email.