The Power of the Planets and the Magic of the Stars: From Natural Philosophy to Necromancy

The Medieval Cosmos

Image copyright The Ordered Universe

This image instantly evokes the beauty of the medieval cosmos. The Earth, as in the classical model on which the medieval version was based, is at the centre, with its known land masses and oceans representing the elements of earth and water. It should be noted that the Earth was thought of as a sphere and not as a flat disc! Wrapping around the earth are the spheres of air and fire, which are ensconced within the spheres of the seven known planets. Closest to Earth is the sphere of the Moon, from which the Moon exerted its ever-changing influence over the tides, the oceans, and the bodily humours of living creatures (including humans). Beyond that sphere are those of Mercury, Venus, the Sun, Mars, Jupiter and Saturn. Each planet had its own set of powers, together with its own pattern of movement around the Earth. Beyond the planets are the spheres of the stars, divided into twelve equal sections named after the signs of the zodiac and the constellations with which they were identified. Still further out is the region marked as Coelum or Heaven, the habitation of God.

The central position of the Earth gives it a special status – but that status came at a price. The Earth is the region subject not only to change and death but also to the powers and influences raining down from all the higher spheres. Therefore, both stars and planets could influence events on Earth. The complexity of this model was greatly increased by the fact that the planets followed routes which brought them into constantly-changing geometrical positions in relation to one another and to the Earth. These inter-relationships caused significant interactions between the powers of the planets involved, which in turn affected their impacts when they reached the Earth. Classical and medieval cosmological theories posited that humans who understood these powers could apply that knowledge in practical ways.

The Zodiac Man and Medicine

The Zodiac Man: Berlin, Staatsbibliothek, MS germ.fol.1191, f.23v (Public Domain Mark 1.0)

This image, known as the Zodiac Man or Man of Signs, shows very strikingly the intimate relationship thought to exist between the human body and the cosmos. The zodiac year began at the Spring equinox, in March, when the Sun entered the sign of Aries. It follows that the highest bodily position is allocated to Aries – and so its symbol, the ram, is depicted resting on top of the man’s head. The rest of the signs are shown in sequence, moving down the body in the order they followed through the solar year, and concluding with Pisces at the feet.

That information was especially important for physicians and surgeons, since it determined good and bad times for carrying out surgery, blood-letting and other medical procedures, depending upon which planet was located in, or powerful in, the sign linked to the relevant body part. For that reason, university courses in medicine included training in the science of the stars, so that physicians could calculate the positions of the planets and act accordingly.

Astrology, Faith, and Free Will

Since the eighteenth century, it has been asserted that this cosmological and medical model was both irrational and superstitious. However, it was not perceived in its own time to be magical. Nevertheless, the distinction between science, magic and superstition became very tricky when questions were asked about the influences of the planets and stars on aspects of human life going beyond bodily health. The Christian Church taught that human beings, having free will, are responsible for their own choices and actions. Secular lawmakers took the same view. It was therefore agreed that, while the stars and planets influence the physical needs and desires of individuals, people make their own decisions. However, that still meant that skilled astrologers could calculate what influences were affecting any given individual.

Astrology and Political Power

It was also accepted that the powers of the planets and stars brought about changes in the Earth’s atmosphere and weather, which in turn would affect the likelihood of disasters such as floods, droughts and crop failures. It followed that those in positions of power and responsibility sought out and consulted respected astrologers. Those who could afford it employed them permanently and asked for their advice not only on personal health and factors affecting their territories but also on things such as when to get married, when and where to have a building constructed, and even when to make an alliance and when to go to war. It is easy to see that the boundary between acceptable and unacceptable questions could be blurred. That was especially the case when it came to the drawing up of personal astrological charts, such as birth charts. If an astrologer could claim to know what an individual was likely to experience – and even to do – did that mean that their life was already mapped out? Could a murderer claim that the stars made them commit their crime?

Horoscopes in Medieval England

Horoscopes: Image Courtesy of the British Library; MS Royal app. 85, f.2

Unsurprisingly, the possibility of foreknowledge of coming events and insights into the future actions of others proved irresistible. It is hardly surprising that very few horoscopes of the forbidden sorts survive, but traces are found in royal archives and records from the twelfth century onwards. The British Library holds a set of horoscopes, drawn up by an anonymous astrologer for an equally anonymous client, asking a series of politically loaded questions about the civil war between King Stephen and the Empress Matilda, which dominated life in England from 1139 to 1153.

Adelard of Bath and the Science of the Stars

What makes these horoscopes tantalising is that the handwriting is that of the Anglo-Norman world in the mid-twelfth century, suggesting that they were drawn up while the war was actually being fought. We also know that there was at least one astrologer in England at the time who had the skills to produce such calculations – Adelard of Bath, who had travelled all the way to Sicily and to Antioch to study many branches of science and magic. Adelard dedicated his treatise on the astrolabe, a scientific instrument central to the ‘new’ science of the stars, to a young prince who is believed to have been the future Henry II of England. The horoscopes themselves contain not only notes on the questions being asked and answered, such as whether an army will come from Normandy, but also boasts about the value of consulting the astrologer!

Astrology Across Cultures

The demand for all such forms of knowledge is shown by the dangerous journeys undertaken by early scholars (like Abelard) in search of astrological training and by the willingness of deeply prejudiced Christian clients to consult Jewish experts. It is also evident in the successful careers enjoyed by some astrologers. For instance, the teacher and astrologer known as Roger of Hereford was employed by Gilbert Foliot, bishop of Hereford 1148-63, and was able to produce works on judicial astrology – one of the more controversial branches of the subject. In that book he even records that he taught astrology to boys in the cathedral school at Hereford. One sample horoscope which Roger illustrated in this textbook concerns a journey to be made by a powerful woman, seeking favour from a king. The point is to illustrate the techniques by which a trained astrologer can judge the likely outcome of such a journey. It follows that a client could also ask about favourable times for important undertakings and gain information about coming events. The famous thirteenth-century astrologer, Guido Bonatti, wrote a textbook on astrology and gave advice to the Emperor Frederick II as well as to many Italian rulers.

The Power of Stones

However, it was possible to go beyond even this. Since it was accepted that the powers of the planets and stars had important effects on all aspects of life on Earth, it followed that it was possible for humans to make use of these powers. Perhaps surprisingly, some parts of this work were acceptable, so long as they simply drew on recognised, though ‘occult’ powers of natural substances which were linked to planetary powers. For instance, Bishop Marbod of Rennes (d.1123) wrote a highly-regarded ‘Book of Stones’, which celebrated the natural-magical powers of many stones. He stated that the sapphire is perhaps the most powerful of all, with the ability to protect anyone who wears it, keep their body healthy, release them from prison, and even make it possible to obtain accurate answers when divining with water. Later lapidaries gave lists of the stones associated with each zodiac sign, and with the planets which ruled them.

Magic, Theology, and Danger

Unsurprisingly, scientists and theologians debated just how powerful such natural substances could be. Theologians in the thirteenth century were increasingly sceptical, and Thomas Aquinas made the definitive statement that if exaggerated claims were made, and especially if mysterious words, names, and talismans were needed to bring about a promised effect, then unnatural, demonic forces were being called upon. Such magic, often called necromancy, was extremely dangerous. As with astrology, warnings did not mean that astral magic was rejected by everyone. That is shown not only by chroniclers who recorded the employment of magicians by the rich and powerful but also by surviving manuscripts giving detailed guidance on when and how to perform magical rituals.

Picatrix and Astral Magic

One of the most famous of these, Picatrix, brought together magical knowledge from Babylonian, Persian, Greek, Arabic and Indian sources. It was edited and translated in the Court of Alfonso X of Leon and Castile, c1256, together with other magical works. Its rituals promised that magicians could produce talismans able to bring about effects such as medical healing, destruction of enemies, successful careers and the acquisition of great wealth. The magician here is both a philosopher and an individual of potentially frightening power, who could contact and control the spirits who acted as intermediaries between the human world and the celestial bodies.

Talismans and Rituals

A talisman of pure silver, made in the hour of Venus and with the Moon in the first, fourth, seventh or tenth house could cast out illness, drive away melancholy and break harmful enchantments. The chosen hour must also fulfil stringent conditions concerning the relations between the Moon, Venus, Mercury and planets with powerful relationships to other houses. A carnelian talisman bearing an image of Venus, with the head of an ass, could cure all gastric problems. This was to be made in an hour of Venus and with Venus in the ascendant. Once completed it could be impressed into wax, which could then be mixed into food and given to the patient. An image of Mercury, engraved in magnetite during the hour of Mercury on the day of Mercury (Wednesday) and with the Moon in Virgo, gave the user great mental powers and ensured that bodies of water, rivers, and all the works of Mercury would be favourable to them.

Spirits, Angels, and the Ars Notoria

Perhaps the most hotly debated part of such astral magic was the nature of the spirits whose help was required. This had serious consequences for users of another well-known magical text, the Ars Notoria, which focused on offering greatly enhanced intellectual powers and knowledge. Users were instructed to fast and prepare for the rituals, before gazing upon strange images while reciting mysterious prayers and strings of unintelligible words and names. An enthusiastic fourteenth-century practitioner, Brother John of Morigny, recorded terrifying dreams in which he was pursued by a demonic creature and only saved by the Virgin Mary. Following these, John produced a new version of the text, emphasising its Christian nature and calling upon angels rather than sinister spirits. As the image below shows, copies of John’s version illustrate these angels very prominently – but that did not protect the work from being condemned and burned in Paris in 1323.

Medieval Magic and the Renaissance

While that condemnation may seem puzzling, it emphasises how seriously magic was taken in medieval Europe, and also that it was far from being restricted to the modern stereotype of the poor and marginalised witch. In fact, medieval magic was the direct precursor of the better-known, learned magic of the Renaissance.