MANILIUS, a Roman poet, was the author of a poem in five books called Astronomica. Nothing is recorded of the author; he is neither quoted nor mentioned by any ancient writer. His very name is uncertain, but was probably Marcus Manilius. From the work itself it may be gathered with much probability that the writer lived under Augustus or Tiberius, and that he was a citizen of and resident in Rome. He bears the name of a distinguished plebeian family. His work is one of great learning; he had studied his subject in the best writers, and generally represents the most advanced views of the ancients on astronomy. It is, however, destitute of poetical or literary merit. It is difficult to explain how a work of such learning on a subject which was studied with such interest by the ancients should have remained so neglected. Firmicus, who wrote in the time of Constantine, has so many points of resemblance with the work of Manilius that he must either have used him or have followed some work that Manilius also followed. As Firmicus says that hardly any Roman except Caesar, Cicero, and Fronto had treated the subject, it is probable that he did not know the work of Manilius. The latest event referred to in the poem is the great defeat of 9 a.d.