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Tetrabiblos

Tetrabiblos, also known as The Four Books of the Influence of the Stars, is a 2nd-century CE treatise attributed to Claudius Ptolemy. Written in Greek, it became one of the most influential works in the history of astrology and was widely studied in both the Islamic and Latin medieval traditions. The text is regarded as a systematic, rational formulation of judicial astrology, aiming to explain how celestial configurations relate to earthly events.

The work is organized into four books, each serving a distinct purpose in the overall system. Book

Book II develops the application of planetary influences as they express themselves through the signs and

Book III shifts to the nativity and the charts themselves. It explains how to determine the significance

Book IV covers techniques for choosing favorable times and places for actions, known as elections, as well

Tetrabiblos’ influence extends through medieval, Islamic, and early modern astrology, where it served as a foundational

I
presents
the
fundamental
theory:
the
zodiac,
the
sun
and
moon,
the
five
visible
planets,
and
the
signs’
natures.
It
introduces
essential
and
accidental
dignities,
enabling
an
evaluator
to
judge
the
strength
or
weakness
of
a
planetary
influence,
and
it
discusses
the
basic
idea
that
planetary
relations
and
aspects
connect
different
parts
of
the
chart.
dignities.
It
provides
rules
for
interpreting
how
a
planet’s
position
in
a
given
sign
conditions
the
probable
outcomes
and
character
of
events,
forming
the
core
methodological
guidance
for
chart
interpretation.
of
planetary
rulers,
the
ascendant
and
the
cusps
of
the
zodiac
houses,
and
how
these
factors
combine
to
produce
a
broader
judgment
about
a
person’s
life
and
fortunes.
as
methods
for
forecasting
outcomes.
It
also
addresses
limitations
and
cautions
relevant
to
predictive
practice.
reference
for
both
theoretical
and
practical
astrology.