Julius Firmicus Maternus

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Julius Firmicus Maternus was a Roman writer of the fourth century, a Sicilian of senatorial standing, known for two books that point in opposite directions. The first, the Mathesis, is the fullest treatise on astrology to survive from the ancient world; the second, De errore profanarum religionum, is a Christian attack on the very kind of religion the astrologer’s art had served. Most scholars hold that one man wrote both. The sole surviving copy of the second work names him Iulius Firmicus Maternus V(ir) C(larissimus) — the title of the clarissimate, the rank of a senator — and that one abbreviation fixes his place: a man of the governing class, writing for the men who ruled with him, in a century when both the heavens and the empire were being reread.

The man and his island

Sicily in the early fourth century was a settled, Latin-speaking province with a deep Greek inheritance, and Firmicus carried both. He addresses the reader as a landowner and a man of affairs, one who has held office and quarreled in the courts, and he writes the literary Latin of the senatorial schools. The Roman Empire of his lifetime was the empire reorganized by Diocletian and refounded by Constantine — a single Mediterranean state with a Christian house at its head and an old aristocracy that still sacrificed, still cast horoscopes, and still moved between the two without embarrassment. Firmicus belonged to that aristocracy, and across two works he moved from one of its instincts to the other.

The Mathesis

The Mathesis — the Greek word máthēsis means “learning,” and came to stand for the mathematical science of the stars — runs to eight books and was composed in the 330s, likely between 334 and 337, dedicated to Lollianus Mavortius, a high official whom Firmicus addresses as consul designate and to whom he had promised the work years before. It is the most extensive astrological treatise in Latin to survive from antiquity, and it sits in the first and oldest stratum of the discipline — the technical Hellenistic astrology preserved chiefly through Vettius Valens, Ptolemy, Dorotheus of Sidon, and Manilius, into which Firmicus enters as the great Latin witness. The doctrine he transmits is older than he is by centuries; what is his is the arrangement, the Latinity, and the survival.

The work is built as a working handbook rather than a defense, though it opens as both. The first two books are an apologia for the art: a defense of the astrologer’s calling against the philosophers who deny that the stars rule us, an account of the cosmos as a single living order in which the heavens and the lower world answer to one another, and an insistence that the practitioner live a clean and honest life. The one who reads the will of heaven, Firmicus argues, must be worthy of the reading — chaste, truthful, free of greed, refusing to cast for questions of the emperor’s death or any matter touching the state. The discipline he describes is bound up with fate: the configuration of the sky at a birth fixes what the native will meet, and the astrologer’s office is to read the decree, not to alter it. This is the determinist register of the art, and Firmicus holds it without flinching even while he reserves a small space for the soul’s freedom under the gods.

From the third book the Mathesis becomes technical. It sets out the meaning of each planet in each of the twelve places, or houses, into which the circle of the sky is divided; the aspects by which the planets see one another across that circle; the antiscia, the mirrored points that pair the signs across the solstitial axis; the decans and the bounds that subdivide each sign; and the influence of the fixed stars beyond the wandering seven. Long stretches are catalogs of outcome — the fortunes, deaths, marriages, exiles, and honors that a given configuration was held to bring — descending in places to the particular fates of those born under named combinations. The eighth book turns to the sphaera barbarica, the non-zodiacal constellations and their risings, material that goes back through Greek sources to older Near Eastern star-lore. Among the planets Saturn holds the heaviest weight, the cold and slow outermost sphere whose lot is limit, loss, and the long reckonings of time — the planet whose character the whole later tradition would inherit largely as Firmicus and his sources set it down.

What makes the Mathesis indispensable is exactly this density. Firmicus writes as a man fully inside the discipline, and he preserves a great deal of older Greek astrological material that would otherwise be lost — schemes and doctrines attested nowhere else, or attested only in fragments. For that reason it remains one of the principal sources for how the art was actually practiced under the empire: not the philosopher’s defense of astrology in the abstract, which is Ptolemy’s Tetrabiblos, but the practitioner’s full apparatus, the thing a working astrologer would consult. He shares the eight-house scheme with Manilius and stands close to the theurgic Platonism of his own century — the world of Iamblichus, for whom the celestial order was woven through with the divine — even as his book stays resolutely technical where Iamblichus turns to rite.

De errore profanarum religionum

The second book belongs to a changed world, or to the same world seen from the other side. Addressed to the emperors Constantius II and Constans, the sons of Constantine, and datable by its internal references to the mid-340s, De errore profanarum religionum — “On the error of the profane religions” — argues that the old cults are demonic error and presses the Christian rulers to suppress them by force. Firmicus takes the mystery religions one by one — the rites of the elements, the dying-and-rising gods, the cult symbols and passwords of the initiates — and reads each as a corruption of a buried truth or an invention of demons, before turning to scripture to demand that the emperors seize the temple treasures and put the worship down. It is among the most unbridled pieces of Christian polemic to come out of late antiquity, and its closing pressure on the rulers to act is direct: the gods of the nations are nothing, and the power that has come to the throne should sweep them away. The text stands at the leading edge of the imperial turn against the old religion — a turn whose later, harder phase would run through Ambrose of Milan against the altar of Victory and, in the next century, through the caesaropapism of Justinian I, under whom the empire’s Christianization became total and the academies of the old learning were closed. That arc is not Firmicus’s doing; he stands near its beginning, urging it on.

One name, two books

The contrast between the two works is stark enough that earlier readers doubted they could share an author: a man steeped in the planets and the demons of the nativity could not, it seemed, be the same who later called those same powers demonic. Across the nineteenth century the two Firmicus works were often assigned to two different writers for just this reason. The identification was argued back together — Clifford Herschel Moore among others made the case — and the prevailing scholarly view now accepts the single author. Jean Rhys Bram, in the introduction to her 1975 English Mathesis, and T. D. Barnes, in his work on the Constantinian age, both read the two books as the work of one man, and read the change between them as a conversion — the common arc of a Roman of his class in the decades after Constantine, when the rewards and the conviction of the new faith were drawing the aristocracy across.

Whether Firmicus saw any tension between casting horoscopes and condemning pagan worship is not something the texts resolve. Astrology and the imperial cult were not the same thing, and a convert might keep the one while renouncing the other: the stars could be read as the instruments of a single providence rather than as gods, and the Mathesis itself already insists on a sober, ascetic practitioner and forbids the questions that touched the state religion most directly. The movement from the one book to the other is not, on this reading, a man repudiating himself, but a man following his class and his century from the temple to the church while keeping the sky.

Transmission and scholarship

The two works came down by very different roads. The Mathesis was copied and consulted through the Middle Ages and into the Renaissance, when it became one of the standard authorities for European practitioners and one of the conduits by which Hellenistic technique reached the later West — the same broad current of recovered ancient and Arabic star-science carried into Latin by translators such as Gerard of Cremona, read and quarreled over by astrologers from Cecco d’Ascoli to William Lilly. It was first printed at Venice in 1497 and again by Aldus Manutius in 1499, in the great folio of the ancient astronomical and astrological writers, and it entered the European canon of astrology and divination from there. De errore fared otherwise: it survives in a single damaged manuscript, the tenth-century Codex Vaticanus Palatinus Latinus 165, and was not printed until 1562 — a polemic that nearly perished, against an art that did not.

The modern critical apparatus rests on the Teubner edition of the Mathesis by Wilhelm Kroll, Franz Skutsch, and Konrat Ziegler, published in two volumes at Leipzig in 1897 and 1913; the first volume, with books one through four, prepared by Kroll and Skutsch, is in the public domain. The Latin text is also maintained, on Pierre Monat’s 2002 edition, in the open digilibLT corpus of late-antique Latin. The standard English version is Jean Rhys Bram’s Ancient Astrology, Theory and Practice (1975). Firmicus is placed within the technical Hellenistic stratum by the standard histories — Tamsyn Barton’s Ancient Astrology (Routledge, 1994), Roger Beck’s A Brief History of Ancient Astrology (Blackwell, 2007), and Nicholas Campion’s A History of Western Astrology, volume one (Continuum, 2008) — while the conversion and its century are the matter of Barnes’s Constantine and Eusebius (Harvard, 1981) and the broader study of the fourth-century Christianization of the Roman governing class. A documentary outline of his life and works is given in the older reference literature, including the Catholic Encyclopedia.

The two works together make Firmicus a useful witness to a hinge moment. He stands at the point where a thousand years of Greco-Roman star-lore was being written down in its most complete Latin form, and where the empire’s official religion was turning against the gods that lore had assumed. Both came down under the same name, and the awkwardness of that pairing is part of what makes him remembered.

→ Related: Divination · William Lilly · Cecco D Ascoli · Ambrose · Astrology · Hellenistic Astrology · Ptolemy · Fate · Saturn · Iamblichus · Gerard Of Cremona · Christianity · Roman Empire · Middle Ages · Justinian I