Both the author and the date of this five-volume poem, the first Western document to link the houses of the zodiac with the course of human affairs, are uncertain. The author's name may be Marcus Manilius, or Manlius, or Mallius, and the latest datable event mentioned in the books themselves is the disastrous defeat of Varus' Roman legions by the German tribes in 9 CE. The writing shows knowledge of the work of Lucretius, but the work is not referred to by any subsequent writer, suggesting that it was never widely disseminated. A manuscript was rediscovered by Poggio Bracciolini in 1416 or 1417, and editions were produced by Scaliger and Bentley, but this immensely erudite edition of 1903–1930 by the scholar and poet A. E. Housman (1859–1936) is regarded as authoritative. Volume 3 describes the working out of horoscopes.