influence of planets on his own and his friends’ natal charts, on past, present and
future events. His deep familiarity with the traditional language of astrology springs
from every page, yet in 1494 Ficino wrote to his friend Poliziano in firm support of
Pico della Mirandola’s attack on astrology, emphasising that “on no occasion” does he
affirm astrological portents, and that, like Pico, he despises the “superstitious vanity”
of the astrologers (Opera omnia).To begin to understand this apparent anomaly, one must look briefly at the tradi-
tion of classical astrology as a rational system of apprehending the workings of the cosmos
which by the fifteenth century was fully established in the West, based on the Aris-
totelian model of celestial causation. Greek and Arabic textbooks on astrology were
passed down via Latin translations, definitively illustrated in the Tetrabiblosof Claudius
Ptolemy, a late Hellenistic work that includes an exposition of the conceptual framework
of astrology. This model implies the correlation of effects from the heavens in an “objec-
tive time” with those on earth, unfolding in a predetermined way like the cogs in a great
machine of destiny. Ptolemaic astrology firmly upholds a natural process of causation, and
introduces the concept of ether, an airy all-pervading substance suffused throughout cre-
ation whose quality depends on the heavenly bodies. Ptolemy promised man the ability
to understand human temperament and predict events through examination of the ether,
and established the primacy of the “seed moment” or moment of origin, such as birth
itself, at which time the heavens stamped an impression that would indelibly mark the
individual. Such a conception of direct, quantifiable astral influence presupposes an
omniscient astrologer who observes objectively a fixed pattern; it appears to allow him to
give an irrevocable judgment on the “fate” sealed by the birth moment. It also implies a
linear unfolding of time and paves the way for modern “scientific” astrological research,
based on statistical analysis, quantitative measurement, and empirical observation.
In the medieval period, orthodox Christianity found no problem with a natur-
al astrology that understood the correspondences between the heavens and the mater-
ial world, and used this knowledge in such fields as agriculture and medicine. But for
denying human free will, and for attributing to the astrologer the omnipotence of
God, judicial astrology was roundly condemned by theologians such as St. Augustine
and Thomas Aquinas, for whom the only legitimate means of foreknowledge could be
through Divine Revelation, as noted in his Summa theologiae.
From this position, there can never be the possibility that divine knowledge
may arise through human effort or activity. The stars cannot be signs in any other way
than they are effects of causes; all true insight into the workings of providence must
depend on an act of grace, on the prayerful submission of the individual’s will to
God’s. In his Disputatio,Ficino clearly set out to fully endorse this view, condemning
the type of astrology that depends solely on human ingenuity and judgment. In his
Letters, he urged the philosophers to gather forces against the “petty ogres” who deny
the sovereignty of God, the justice of the angels, and the freewill of men, “that we
may triumph over the diviners, albeit not divine but mightily profane, who have for so
long been shackling us to their illusions.”
This would appear to be a definitive statement of allegiance to the orthodox
position. Yet a closer reading shows something new. Although Ficino rejected certainFicino, Marsilio
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