trial orbit), exert benefic (“good”) or malefic (“bad”) astrological influences, and so
forth. (Seethe individual entries on the planets for more information.)Sources:
Campion, Nicholas. The Practical Astrologer.New York: Harry N. Abrams, 1987.
DeVore, Nicholas. Encyclopedia of Astrology.New York: Philosophical Library, 1949.
McEvers, Joan. Planets: The Astrological Tools.Saint Paul, MN: Llewellyn Publications, 1989.PLATIC
Astrologers allow individual aspects a particular orb of influence within which they
are regarded as having an effect. Nonexact aspects are referred to as platic aspects and
are considered to have a weaker influence than partile (exact) aspects.PLATO
Plato, the most famous of all Greek philosophers, lived in Athens from approximately
427 B.C.E. to 347 B.C.E. Although some sources have claimed that Plato lived for a
period in Egypt and studied astrology, this is not reflected in his writings. Plato’s signif-
icance for astrology is that directly through his own surviving works and indirectly
through the Neoplatonic tradition, he was the most influential advocate of the idea
that the human being is a miniature version (microcosm) of the larger universe
(macrocosm). The microcosm and the macrocosm are linked by—and affect each
other through—certain correlations. This notion is basic to ancient astrology.PLOTINUS
Plotinus, the greatest Roman neoplatonist, lived from approximately 205 to 270 C.E.
He studied in Alexandria, Egypt, one of the centers of learning that preserved classical
astrology, magic, and medicine (Alexandrian neoplatonists were responsible for the
survival of astrological science in the West). Plotinus accepted astrology but was
opposed to a deterministic view of planetary influence. Like Plato (from whom the
term neoplatonism is derived), Plotinus is not important for any direct contribution to
astrology but for the elaboration and propagation of the Pythagorean view that the
individual human being is linked to the greater cosmos through a system of correla-
tions—a view that is a foundation stone of ancient astrological theory.PLUTO
Pluto is the farthest known planet from the Sun and by far the smallest with a diameter
of 1,444 miles and a mass only 2 percent that of the Earth. Pluto completes an orbit of
the Sun every 247.69 years, meaning that it spends more than 20 years in each sign of
the zodiac. Thus, an entire generation is born while Pluto is transiting each sign.
The existence of a ninth planet was suspected when astronomers detected a
gravitational affect on the orbit of Neptune. Percival Lowell, an American astronomer,
built a private observatory in Flagstaff, Arizona, called Lowell Observatory in order toPlatic
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