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Liber III · Black & White Magic

Liber III · Black & White Magic · Chapter VIII: Theories of Magic

Speculum Astronomiae: Astrology, Images and Forbidden Books

The Speculum astronomiae (c. 1260), attributed to Albertus Magnus: how it defended astrology, classed astrological images and named Solomonic necromancy.

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The Speculum astronomiae ("Mirror of Astronomy") is a short Latin treatise written around 1260 and attributed since the Middle Ages to the Dominican scholar Albertus Magnus. It was composed to separate the respectable science of the stars from books of magic that disguised themselves as astronomy: it lists the approved works of astronomy and astrology, defends astrology against the charge that it destroys free will, and sorts books of astrological images into the licit and the condemned, naming several necromantic texts attributed to Solomon.

Purpose and Setting of the Speculum Astronomiae§

The thirteenth century saw the Latin West absorb a great body of Arabic astronomy, astrology and magic, translated in Spain and Italy during the previous hundred years. Universities taught astronomy as one of the liberal arts, and physicians relied on astrology for timing treatment. At the same time, manuscripts of ritual and image magic circulated under the names of Hermes, Solomon, Ptolemy and other authorities, and theologians worried that the two kinds of learning were becoming confused.

The Speculum addresses that confusion directly. Its author explains that he writes because of certain books whose authors pretend to treat of the stars but in fact contain necromancy, and which have brought honest astronomical works under suspicion. His solution is a reasoned catalogue: by listing the genuine books with their opening words, so that readers could identify them, and setting apart the suspect ones, he hoped to protect the science from guilt by association. The result is a valuable snapshot of what was available to a Latin reader around 1260.

The Two Great Wisdoms: Astronomy and Judicial Astrology§

The Speculum begins by distinguishing two "great wisdoms" concerning the heavens. The first studies the configuration and motions of the celestial spheres; its books include Ptolemy's Almagest and the works of Arabic astronomers such as al-Farghani and Thabit ibn Qurra in Latin translation. This part of the science was mathematical and uncontroversial.

The second wisdom is the science of the judgements of the stars, the study of how celestial bodies influence the lower world. Here the author lists the Quadripartitum of Ptolemy, better known today as the Tetrabiblos, together with works by Abu Ma'shar (Albumasar), Masha'allah (Messahala), Sahl ibn Bishr (Zael), al-Qabisi (Alcabitius) and others. He divides judicial astrology into its traditional branches: the revolutions of the years and world events, nativities, interrogations or questions, and elections of favourable times for action. Each branch is described and its principal books identified, so that a reader could recognise the canonical texts.

The author then confronts the theological objection that astrology implies determinism. Drawing on a long scholastic tradition, he argues that the stars incline but do not compel: they act on bodies and through them dispose the will, but a wise person, aided by reason and grace, can resist their influence. Knowledge of the heavens therefore helps rather than harms human freedom, much as a physician's foresight helps a patient. This argument became a commonplace in later defences of astrology, and the wider history of that discipline is outlined in astrology: a complete guide.

The Science of Images: Abominable, Detestable and Acceptable§

The most influential part of the Speculum concerns astrological images: figures engraved or cast under particular configurations of the heavens and believed to channel celestial power for healing, protection, love, discord or other ends. Image magic was one of the most prestigious forms of learned magic, transmitted through works such as the Picatrix, and it sat uneasily between natural philosophy and demonic ritual.

The author arranges image books into three kinds. The first, which he calls abominable, requires suffumigation and invocation, so that the image works by addressing spirits; he associates this kind with books under the names of Hermes and other ancient authorities. The second, detestable, requires the inscription of characters and the exorcism of names, which he regards as a means of communicating with demons; it is here that he places the books of Solomon. The third kind works, he says, only through the figure of the heavens at the moment of making, without invocations, suffumigations or characters, and is therefore a natural operation that may be permitted.

This threefold scheme was enormously important. Nicolas Weill-Parot has shown that it helped set the terms of debate on "astrological images" for three centuries, a debate that engaged thinkers from Thomas Aquinas, who was more sceptical of purely natural images, to Marsilio Ficino, who used a comparable distinction in his treatise on medicine and celestial influence (Ficino's Three Books on Life). The question of whether an image could act by nature alone, or whether any sign necessarily addressed an intelligence, is central to the medieval theory of astral magic.

The Books of Solomon in the Speculum§

The Speculum is one of the earliest witnesses to a Latin Solomonic magical literature. Among the necromantic books whose use of characters and exorcisms it condemns, the author names works ascribed to Solomon, including a book of the four rings, a book of the nine candarii (a word of uncertain meaning, perhaps referring to figures or tablets), a book of the three figures of the spirits, a book of seals for the possessed and the Almandal, a ritual of a consecrated altar or tablet whose later forms survive as the Almadel of the Lemegeton.

These titles show that by the mid-thirteenth century a body of ritual magic circulated under Solomon's name, long before the Key of Solomon or the Lesser Key took the forms in which they are known today. Several of the works the Speculum mentions can be matched with surviving manuscripts, while others are known only from such lists. The Speculum was copied and cited for centuries, and later cataloguers of magic, including Johannes Trithemius in his Antipalus maleficiorum, followed its practice of naming the forbidden books.

The author's attitude to these texts is notable. He condemns them, but he does not call for their destruction. Towards the end of the work he suggests that it may be better to set such books aside than to burn them, since a time might come when it would be useful to have examined them. This cautious position, which treats even dangerous books as objects of knowledge, contrasts with the burnings of magical books that ecclesiastical authorities sometimes ordered.

The Authorship Debate: Albertus Magnus or Another?§

Albertus Magnus (c. 1200–1280) was a Dominican friar, bishop of Regensburg for a short time and the teacher of Thomas Aquinas, famous for his encyclopaedic commentaries on Aristotle and his writings on minerals, plants and animals. His reputation for learning made him a magnet for attributions, and many later books of secrets and charms, such as the Grand Albert and the Petit Albert, were published under his name without any real connection to him.

The Speculum is different, because it is attributed to Albert in medieval manuscripts and its views are close to those in his authentic works, where he also discusses the powers of stones and images. Paola Zambelli, in a major study published in 1992, argued that Albert was indeed the author. Agostino Paravicini Bagliani, examining the manuscript tradition, questioned the attribution and proposed other candidates from the scholarly world around the papal court, including the mathematician Campanus of Novara. The question remains open, and many historians now cite the work as "attributed to Albertus Magnus".

Influence and Significance§

The Speculum astronomiae mattered because it gave a respectable formula for coexistence between the Church and the science of the stars. In 1277 the bishop of Paris, Étienne Tempier, condemned a long list of philosophical propositions together with books of necromancy and invocation of demons, and the line drawn in the Speculum between legitimate astrology and forbidden magic helped defenders of astrology to argue that their discipline fell on the right side. Its classification of images informed later debates among theologians and humanists, and its bibliography remains a key source for historians who reconstruct the medieval magical library.

The work also illustrates a pattern found throughout this period: magic was defined largely by its critics, through lists of forbidden practices and books. Similar efforts by Roger Bacon, discussed in Roger Bacon and magic, and later by theologians examined in how theologians judged demonic magic, drew boundaries that practitioners themselves often contested.

Frequently asked questions§

What is the Speculum astronomiae?§

It is a Latin treatise of about 1260, usually attributed to Albertus Magnus, that lists and evaluates books of astronomy and astrology. It defends astrology as compatible with free will and distinguishes acceptable astrological images from those that involve invoking spirits.

Did Albertus Magnus write the Speculum astronomiae?§

Its authorship is uncertain. Medieval manuscripts attribute it to Albert, and Paola Zambelli has argued in favour of his authorship, while Agostino Paravicini Bagliani and others have doubted it and suggested authors from the papal circle.

Which Solomonic books does the Speculum mention?§

It names several works attributed to Solomon among the condemned books of image magic, including books of the four rings, of the nine candarii, of the three figures of the spirits, of seals for the possessed and the Almandal. These are among the earliest references to Latin Solomonic magic.

What are "detestable" images in the Speculum?§

The Speculum calls detestable those images that work by inscribing characters and exorcising names, which it considered a way of dealing with demons. It distinguishes them from abominable images, which use suffumigation and invocation, and from images that act through celestial influence alone.

Sources and further reading§