Astrology and Christian Doctrine: From Medieval Synthesis to Renaissance Hermeticism

Those admissible to genuine Christian doctrine and those contrary to it. In short, the idea emerges of purifying astrology both from all those necromantic and execrable practices of the texts that were circulating, as well as the idea of clarifying this relationship between man and his destiny, between astrology and free will. Albertus Magnus responds to both these needs. To the first with the Speculum Astronomiae, a 1270 writing generally attributed to Albertus Magnus, which primarily distinguishes licit from illicit books, practices, and astrological images, to defend and purify virtuous Astrology from numerous necromantic writings of dubious provenance that were proliferating in Europe at the time.

For the second, although the theme of free will is also one of the fundamental themes treated in the Speculum Astronomiae, nevertheless Albertus Magnus's clearest position on the matter is clearly expressed in other books whose authorship is assured, such as in his book on the Nature and Origin of the Soul:

Dante and Cecco d'Ascoli

The position is taken up by the great intellectuals of the 14th century, such as Dante and Cecco d'Ascoli. Cecco d'Ascoli will say that the influence of the planets acts only if the soul becomes vile, servile and thievish:


While by its nature it should be a dominating lady over the other stars:


The same words are pronounced by Dante in the Divine Comedy in the XVI canto of Purgatory:

Magical Astrology

Around the middle of the 15th century at the Medici court there was considerable cultural ferment and particular attention toward Hellenic culture catalyzed by a series of conferences held by Gemistus Pletho, a Neoplatonic philosopher who had a certain influence on Cosimo the Elder. The inspiring conferences of Gemistus Pletho, together probably with the confrontation with numerous scholars from the Eastern Roman Empire present in Florence for the council that was supposed to heal the Eastern schism, induced Cosimo de' Medici to establish in 1459 a Platonic Academy whose purpose was to rediscover and bring to light Plato's work with new translations of his dialogues.

In this extremely fertile context it happened that in 1460 the monk Leonardo da Pistoia managed to find in Macedonia and thus bring back to Cosimo's court a manuscript codex, probably belonging to Michael Psellus, the renowned 11th-century Byzantine scholar, containing fourteen of the now eighteen treatises to which the Asclepius must be added. Cosimo de' Medici immediately understands the value of the Codex, asks Ficino to interrupt his translation of Plato and begin translating this other codex. Thus in 1471 the first edition of the Corpus Hermeticum translated into Latin under the name Poimandres was published.

The role that this publication had at the time is difficult to render in few words. One must consider indeed that Europe had been eager for more than three centuries to have a reliable corpus of treatises by this Egyptian personage who was King like David, Philosopher like Plato, and Prophet like Moses. One must also consider that the codex translated by Ficino, perhaps precisely due to its previous belonging to Michael Psellus who was an Orthodox monk and who had probably purged the text, integrated perfectly with Christian doctrine and theology, so much as to promote common reflection on the existence of a prisca, or "most ancient" theology preceding every religion, independent of every cultural contingency and always valid.

And as confirmed by the introduction to the Corpus Hermeticum made by Marsilio Ficino in the dedication to Cosimo de' Medici, where he identifies Hermes Trismegistus as indirect master of Pythagoras and Plato:


The Corpus Hermeticum thus had incredible diffusion that led it to have as many as sixteen reprints from the first publication date of 1471 until the end of the sixteenth century. All the greatest philosophers, scientists and intellectuals of the era would be profoundly indebted to it.

Hermetic doctrines had incredible weight in the development of modern scientific thought - one need only think that Copernicus in supporting the heliocentric theory brings as authoritative reference that of Hermes Trismegistus:


For example, in the XVI discourse of the Corpus Hermeticum one finds the passage that will inspire heliocentric theories: "But a vision..."