These articles on the history of astrology
in the Renaissance were originally published in the Mountain Astrologer.
You can start the series at the Astrology in the Renaissance
Main Page.
One of the most characteristic components of the
Renaissance was the trend towards humanism, a revival of classical knowledge.
This rediscovery of the knowledge of antiquity also took place in astrology;
astrologers increasingly turned to Ptolemy as the exemplar of "true" classical astrology.
Claudius Ptolemy was an Alexandrian Greek who
lived in the 2nd century A.D. His Tetrabiblos, a basic text of astrology,
was always highly regarded, but during the Renaissance, astrologers began
to consider it canonical and to reject any astrological doctrine or technique that
it did not include. Some branches of astrology, like horary and electional,
or techniques like firdaria were branded "Arabic inventions" because they
do not appear in Tetrabiblos. (Ironically, some modern scholars have
speculated that Ptolemy was not even a practicing astrologer, noting that
he provided no examples and fails to mention such basic techniques as the
influences of the planets in the signs and houses.)
Along with a revival of classical astrology,
the Renaissance saw many efforts to test and refine astrology. Many astrologers
began to systematically collect and annotate natal charts in an effort to
systematize and increase the quality of delineation.
The work of Italian astrologer Luca Gaurico
was typical of these efforts. In 1552 he published his Tractatus Astrologicus
which gave charts of the foundation of various buildings and cities as well as
the natal charts of popes, cardinals and other eminent religious leaders, kings
and nobles, scholars, musicians and artists. Gaurico carefully examined each
natal chart, compared it to the life of the native, and in the case of living
subjects, predicted the outcome of their lives and careers.
Lynn Thorndike, History of Magic and Experimental Science, Vol. IV, page 100
(New York, Columbia, 1941).
Many astrologers published their own
collections of natal charts, and
popular interest in the nativities and futures of the kings, popes and
other eminent persons featured made for a number of Renaissance "best sellers".
Renaissance astrologers also made numerous
advances in technique. A number of new house systems including the Campanus
and Regiomantanus systems were invented or more widely dispersed.
New ephemerides were compiled, increasing the accuracy of chart erection.
Ironically, Copernicus, who is considered by modern skeptics to have disproved
astrology by discovering heliocentric astronomy, made a major contribution
to astrology. Based on Copernicus' work, Erasmus Reinhold in 1551 published
new astronomical tables, known as the Prutenic Tables, which greatly aided
astrologers in the accuracy of their computations.
Similarly, while Johann
Kepler is renowned by modern scientists as an astronomer, he practiced as an
astrologer, and in 1627 published the Rudolphine Tables which further improved
the accuracy of astrological prediction and delineation.
One of the most ambitious projects to advance and
rationalize astrology was undertaken by the French astrologer Jean Baptiste Morin.
His Astrologica Gallica, published in 1661, is a monumental work
and provides a philosophical and rational basis for astrology as well as
a complete system of delineation.
Morin carefully examined astrological
doctrine, discarding those portions he found to be inaccurate or ineffectual
and substituting his own methods, based upon his own systemic theory or experience.
Morin systematically dealt with directions, revolutions of nativities and of years,
progressions, transits, planetary conjunctions, eclipses, comets, as well as
horary and electional astrology. It is unfortunate that only portions of
Astrologia Gallica have been translated into English, given its great
scope and penetrating insights.