Effects by Pseudo-Manetho

The Effects is a didactic poem in Greek hexameters on genethlialogy, the reading of nativities, transmitted under the name of Manetho. Its subject is what the heavenly bodies bring about in a human life. The book that stands first in the transmitted text begins with the structure of the heavens, the fixed stars, the five wandering planets, the axis, the poles and the circles of the sphere, and then sets out what each of the seven planets effects in its own house and in another's, at its rising and setting, and in its phases with the Sun and the Moon. Across six books the poem works through planetary configurations and their consequences: trades and professions, character, marriage and children, wealth and poverty, illness and injury, madness, and manner of death. A characteristic passage tells how Mars, Saturn and Mercury in certain positions blind, derange or impoverish the native.

One proem addresses a King Ptolemy and presents the teaching as drawn from the sacred writings of the Egyptian temples, in the person of Manetho of Sebennytos, the early Ptolemaic priest who wrote a history of Egypt. The frame is pseudepigraphic: the language, the doctrine and the evidence within the poem place it in the Roman imperial period. The work is composite, generally held to be by two or three poets writing at different times; one layer appears to contain the poet's own nativity, usually taken to point to the late first century CE, while other books are later. The attribution and dating of each part remain debated.

The poem survives essentially in a single medieval manuscript, whose order and numbering of the books do not follow their content; the standard edition is Koechly's. With the fragments of Dorotheus of Sidon, it is one of the few substantial Greek astrological poems to survive, and its catalogues of occupations and conditions of life make it a source for the social history of the Roman world.