Marcus Manilius is an enigma, and an enigma not often sought out. Even his name is uncertain, the "Marcus" is partly conjectural. All that we know of this man comes from his sole, known work, his didactic monograph, the "Astronomica", a five book Latin poem that discusses astrology and Stoicism.

The poem is bereft of direct biographical content, however, we can deduce that he was intelligent, knowledgeable of his subject matter, and a devotee of both astrology and the philosophy of the Stoa—the two are one and the same, each an expression of the other—to Manilius.

It is also likely that he was well connected. The imperial family of Augustus delved into astrology and philosophy from time to time. Augustus' successor, the dour Tiberius, had his own, personal astrologer, the famous Thrasyllus, while occasionally persecuting and exiling other astrologers due to the potential social upsets (speculating on the date of the emperor's death) they might cause.

It is most likely that the poem was first composed in the last years of Augustus (~10-14 CE), and completed under Tiberus (the 20s CE). The first book of the poem is dedicated to Augustus, and the latest date is the 9 CE defeat of the three legions of Varius, governor of Germany, by rebellious tribes.