This is a very detailed review of what is known about the eastern religions which were absorbed into Roman Paganism during the late Republic and Imperial periods. Cumont, who also wrote The Mysteries of Mithra was a Belgian scholar who specialized in the study of ancient religion. Topics include the cults of the Magna Mater, Cyblele, Isis, Astarte, Mithrism and Zoroastrianism, as well as a study of astrology and how it became part of Roman beliefs. Roman Paganism started out as a system of animist beliefs with a simple pantheon of gods and goddesses. Contact with these diverse near-eastern religions added a sophisticated system of ethics, ritual and cosmology and a host of additional deities.