Astronomica, also known as the Astronomicon, is a Latin didactic poem about celestial phenomena, written in hexameters, and divided into five books.

The Astronomica was written c. AD 30–40 by a Roman poet whose name was likely Marcus Manilius; little is known of Manilius, and although there is evidence that the Astronomica was probably read by many other Roman writers, no surviving works explicitly quote him.

The earliest work on astrology that is extensive, comprehensible, and mostly intact, the Astronomica describes celestial phenomena, and, in particular, the zodiac and astrology. The poem—which seems to have been inspired by Lucretius’s Epicurean poem De rerum natura—espouses a Stoic, deterministic understanding of a universe overseen by a god and governed by reason.

The fifth book of the Astronomica features a lacuna, which has led to a debate about the original size of the poem; some scholars have argued that whole books have been lost over the years, whereas others believe only a small section of the work is missing.

The poem was rediscovered c. 1416–1417 by the Italian humanist and scholar Poggio Bracciolini, who had a copy made from which the modern text derives. Upon its rediscovery, the Astronomica was read, commented upon, and edited by a number of scholars. Nevertheless, it failed to become as popular as other classical Latin poems and was neglected for centuries.

This started to change during the early 20th century when, between 1903 and 1930, the classicist A. E. Housman published a critically acclaimed edition of the poem in five books. Housman’s work was followed by the Latinist G. P. Goold’s lauded English translation in 1977.

Today, scholars consider the Astronomica to be highly technical, complicated, and occasionally contradictory. At the same time, many have praised Manilius’s ability to translate highly technical astronomical concepts and complex mathematical computations into poetry.


According to Volk, Manilius’s Astronomica is the earliest work on astrology that is extensive, comprehensible, and most extant.

Volk wrote that since he dedicates the poem to stellar phenomena, it is:

“indicative of the great fascination … that the stars held for the Romans of Manilius’ period”.


The Astronomica, which is written in hexameters, opens with Manilius contending that he is the “first to sing of astrology“. He also claims that the god Mercury engendered his interest in celestial bodies.

First book

In the first book, he ponders the origin of the universe, considering theories by Xenophanes, Hesiod, Leucippus, Heraclitus, Thales, and Empedocles before arguing that the universe was created from the four elements and is governed by a divine spirit.

According to Manilius, the universe is composed of two spheres: one—the Earth—is solid and the other—the “sphere of stars“, often called the firmament— is hollow. The constellations are fixed in the firmament; the Earth is stationary and the firmament revolves around it, explaining the movements of the stars.

The planets, the Moon, and the Sun also revolve around the Earth in the vast space between its surface and the edge of the firmament. Because the Earth is in the center of the universe, it is equidistant from the firmament and is thus not compelled to “fall” in any specific direction.

According to Manilius, the universe is ruled by a god (conspirat deus) and is governed by reason (ratione gubernat). Manilius next discusses the constellations and stars and the celestial circles. In this section, the poet spends considerable time contemplating the Milky Way band, which, after exploring several hypotheses as to its existence, he concludes is likely the celestial abode for dead heroes.

The first book ends with an exploration of comets, which Manilius sees as harbingers of calamity or great disaster.

Second book

Book two opens with a preface in which Manilius presents a brief history of hexameter poetry, singling out Homer and Hesiod. The purpose, Volk argues, is to emphasize the uniqueness of his poem in comparison to others rather than to insert himself into this poetic tradition.

According to Manilius, “Every path that leads to Helicon has been trodden” (omnis ad accessus Heliconos semita trita est; all other topics have been covered) and he must find “untouched meadows and water” for his poetry: astrology.

Manilius ends the book’s preface by saying “that the divine cosmos is voluntarily revealing itself both to mankind as a whole and to the poet in particular“, and that he is set apart from the crowd because his poetic mission has been sanctioned by fate.

The poet then begins his explanation of the first astrologically significant circle: the zodiac itself. He first considers the signs of the zodiac (viz. Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, and Pisces), before discussing the aspects and relationships between the signs and other objects. In this section, the poet briefly discusses the zodiac signs, the Olympian gods who serve as their protectors, and the relationship between the signs and the parts of the human body.

The Astronomica then considers dodecatemoria before he deviates from the zodiac and begins to discuss the didactic method.

The book concludes with a consideration of the second astrologically significant circle, that of the fixed circle of the observer. The last few lines are dedicated to an overview of the dodecatropos.

Third book

The third book—which focuses mainly on “determining the degree of the ecliptic which is rising about the horizon at the moment” of a person’s birth—opens with Manilius’s reiteration that his work is original.

Because his topic is complex and difficult, the poet tells his audience they can “expect truth but not beauty“. He then discusses the third astrologically significant circle, the lots, which are points on a birth chart that carry special significance.

Subsequent verses explain how to calculate the ascendant, the horoscope, and chronocrators; and how to determine the projected length of one’s life. The third book concludes with a discussion about the tropic signs, which, while not particularly pertinent to the astrological content of the book, allows Manilius to end the book on a “poetic note“.

Most scholars consider the third book to be highly technical; according to Goold it:

“is the least poetical of the five, exemplifying, for the most part, Manilius’s skill in rendering numbers and arithmetical calculations in hexameters”.

A similar but less favorable sentiment is expressed by Green, who writes that in this book:

“the disjuncture between instruction and medium is most obviously felt [because] complex mathematical calculations are confined to hexameter and obscured behind poetic periphrasis”.

Fourth book

Book four covers many topics that originated in Egypt, leading Goold to write that Manilius based his work on an Egyptian source.

Much of the first portion of this book deals with decans and the partes damnandae, both of which allow Manilius another chance to convert mathematical and astrological tables into poetic verse. A short description of the rising of individual zodiacal degrees is followed by a more comprehensive survey of zodiacal geography. Near the end of the book, Manilius writes about the ecliptic signs.

The book is punctuated at lines 4.387–407 and 4.866–935 by “exhortation[s] of the frustrated student“, where complaints that astrology is difficult and nature is hidden are countered by statements that “the object of study is nothing less than (union with) god” and “the universe (microcosm) wishes to reveal itself to man“.

Fifth book

Most of the fifth (and final) book is a discussion of paranatellonta via the myth of Andromeda and Perseus. Manilius recalls how Andromeda was chosen to be sacrificed to a sea monster by her parents; Cepheus and Cassiopeia.

Andromeda was chained to a cliff but before the creature could consume her, Perseus (who had just vanquished Medusa) arrived. He instantly fell in love with Andromeda, killed the sea monster, and saved the young woman’s life.

According to Green, the digression, which is by far the longest in the poem:

“is very well chosen, in as much as no other mythological episode involves so many future constellations interacting at the same time; Andromeda, Perseus, the Sea Monster—strictly, Cetus (cf. 5.600), but often referred to in more generic terms during this story as belua and monstrum —Medusa’s head, and Andromeda’s parents, Cepheus and Cassiopeia”.

Green says the story is perfect for Manilius; he is able to use it to justify the constellations’ proximity to one another and their eternal arrangement, as he had previously argued in 1.354–360.

Conversely, Housman compared it unfavorably to Ovid’s version of the story and called Manilius’s retelling “a sewn-on patch of far from the best purple“.

A similar sentiment was expressed by the Cambridge classicist Arthur Woollgar Verrall, who wrote that while the episode was meant to be a “showpiece“, it comes across as “a poor mixture of childish rhetoric and utter commonplace“.

Between lines 5.709–10, there is a large lacuna, meaning that at least some of the work is missing, and then the last few lines of the book concern stars and other stellar phenomena. The book ends with a simile about the “res publica of stars“.

This section—in which Manilius proposes that the stars constitute an elaborate and organized system, defined by a hierarchy that prevents “cosmic disaster“—seems to be a way for Manilius to assert the legitimacy of the Roman state through analogy.


According to Volk:

“The basic tenet of what we might call Manilius’ natural philosophy is the idea that the universe is divine”.

She writes that Manilius is inconsistent about the location of this divinity. For instance, in his first book, Manilius claims the perfectly regular movement of the sun, moon, planets, and stars is proof that the universe is the product of a god; he also says the universe itself is a god (mundum … ipsum esse deum).

Later in the same book, Manilius again says the universe is the “work of a great divinity” (magni … numinis ordo). Concerning this vacillation, Volk writes:

“It is clear that there is a certain elasticity to Manilius’ concept of the divinity of the universe … Is the world simply ruled by a diuinum numen (cf. 1.484) or is it a deus (cf 1.485) itself?”

Volk answers that in the cosmology of the Astronomica:

“God can be understood as the soul or breath … present within the world [and] since this divine entity completely pervades the cosmos, it makes equally much sense to call the cosmos itself a god”.

According to Volk, this interpretation of the universe, which states that it has a sense of intellect and that it operates in an orderly way, thus allows Manilius to contend both that there is an unbroken chain of cause and effect affecting everything within the cosmos and that fate rules all.

Volk points out the poem borrows or alludes to a number of philosophical traditions, including Hermeticism, Platonism, and Pythagoreanism but the prevailing belief of commentators is that Manilius espouses a Stoic worldview in the Astronomica.

A comparison between Manilius’s beliefs and those of other Stoics reveals parallels that according to Volk “are immediately obvious”.

For instance, Stoics and Manilius agree on the divinity of the universe, the argument from design, the assumption that the supreme god is both the creator of the universe and the active force within it, the interconnectedness of everything, the understanding that humans are intimately connected to the cosmos, the importance of considering the heavens, and the belief in an inescapable fate that rules overall.

The agreement on this latter point is of special importance because, according to Volk, belief in fate is “one of the most notorious aspects of the Stoic system“.

The identification of the poem as Stoic, however, is not unanimous. In 1887, against the common opinion of contemporaneous scholars, Gustave Lanson contested the idea that the poem is Stoic.

In 2005, Alexander MacGregor said that while contemporary scholars such as Goold and Volk read Manilius as a Stoic, the Astronomica actually breaks with or contradicts Stoic tradition in a number of places. Manilius exalts Plato, Socrates, and Pythagoras; proposes a Platonic proof for the existence of God, denies the ekpyrosis (a key Stoic belief in the periodic destruction of the cosmos by an immense conflagration every Great Year followed by a cosmic recreation), never discusses the six Stoic paradoxes as discussed by Cicero, and ignores the importance of controlling the soul.

Manilius also focuses on a number of Pythagorean tenets; the Pythagorean order of the planets, the importance of geometry and numbers, and the significance of tetraktys (triangular figures made up of ten points arranged in four rows).

In key places, Manilius also makes use of non-Stoics like Eudoxus of Cnidus and Cicero. Given these factors, MacGregor concludes that Manilius should be classified as an idealistic Pythagorean or a Platonist rather than a Stoic.


Manilius frequently imitates Lucretius, who wrote the didactic poem De rerum natura. Some classicists have suggested that Manilius may have sought to emulate Lucretius by writing six books, but evidence for this hypothesis is scarce, and it remains mostly speculative.

While Lucretius’s work espouses Epicureanism (a philosophy that emphasizes materialism and skepticism of superstition and divine intervention), Manilius’s work is largely Stoic and promotes a Greco-Roman understanding of creationism as well as fatalistic determinism.

Both Volk and the Lucretian scholar David Butterfield have argued that Manilius is in many ways, an “anti-Lucretius“, with the former arguing that:

“his presentation in the Astronomica of an orderly cosmos ruled by fate is a direct attack on the random universe depicted by his predecessor”.

Manilius sometimes conveys his philosophical stance via grammatical voice: unlike Lucretius, who often uses a passive construction to convey his understanding of nature, Manilius uses active grammatical constructions to convey the intentionality he sees in creation (e.g. “God and reason, which rules all things, guide earthly animals by heavenly signs”).

Furthermore, while Lucretius used De rerum natura to present a non-theistic account of creation, Manilius “was a creationist rather than a materialistic evolutionist“, and he consequently refers to “one spirit“, a “divine power“, a “creator“, and a “god” throughout his poem.

The Astronomica is influenced by Ovid’s Metamorphoses, Virgil’s Aeneid, Ennius’s Annales, and the Greek didactic poet Aratus. The latter’s influence on Manilius is especially noticeable, and it seems likely that Manilius based much of his first book on portions of Aratus’s Phaenomena.

Despite his debt to the poet, Manilius diverges from his understanding of the cosmos; Aratus focuses on mythology and “graphic description“, whereas Manilius emphasizes the scientific aspects of his work. It is uncertain if Manilius had direct knowledge of Aratus’s poem or if he used a translation by Cicero, Ovid, or Germanicus.

The latter position is favored by several 21st-century scholars, such as Dora Liuzzi and Emma Gee. In regards to the poet’s relationship with Germanicus, Wolfgang Hübner writes:

“The few echoes of Germanicus’ translation of Aratus are insufficient for us to establish which of the two drew on the other, or whether the two were composed independently of each other.”

The Astronomica directly references Homer (as the “greatest poet”, maximus vates) as well as Hesiod (calling him “nearest to [Homer]”, proximus illi), and alludes to numerous other Greek poets and writers such as Apollonius Rhodius, Choerilus of Iasus, Choerilus of Samos, and Aeschylus.

The poem also contains a direct allusion to Ennius’s Annales, which, according to Goold, is the Astronomica’s “one solitary notice of Latin literature.

*This article uses material from the Wikipedia article Astronomica which is released under the Creative Commons Attribution-ShareAlike License 3.0 (view authors).