Paulus Alexandrinus was an astrological author from the late Roman Empire. His extant work, Eisagogika, or Introductory Matters (or Introduction), which was written in 378 AD, is a treatment of major topics in astrology as practiced in the fourth century Roman Empire.
Little is known about Paulus' life. He lived in Alexandria, one of the most scholarly cities of the Roman world, where astrology was also at its most sophisticated. In his lifetime, Rome's power was declining and the capital of the Roman Empire had been moved to Constantinople. We know he was regarded as a considerable authority because we have the record of a series of lectures given on his work by the respected Neo-Platonist philosopher Olympiodorus some two centuries later (in 564 AD), in Alexandria. These lectures were preserved in a Commentary and both Paulus' Introduction and Olympiodorus' Commentary have been translated together, giving a view of the development of astrological technique and contemporary attitudes towards astrology from the tumultuous late Empire through the even more unstable early Byzantine Empire.
The Introduction may be most interesting for its discussion of the eleven phases of the Moon, because it gives us a clear treatment of a topic whose influence on Greek astrological speculation has likely been much underestimated The Moon's phases are probably the single most influential factor in katarchic charts of the Hellenistic period, going back beyond Dorotheus of Sidon. Also very important in the Introduction are the Lots, which were at the core of Hellenistic astrological technique, although the scientifically minded Ptolemy avoids them. Paulus also discusses dodekatemoria and monomoiria, and gives an extensive treatment of sect in astrological analysis, and of the influence of planetary aspects as they apply and separate (the Hellenistic understanding of which is considerably at odds with modern practice.)