One highly influential form of divination in the ancient world, which also had a major impact on the casting of spells and creation of charms, was astrology. The ancients, whether Egyptian, Babylonian, Persian, Greek, or Roman, all paid close attention to the sun, the moon, and the five visible planets. They regarded this seven “wandering stars” in particular as divine entities whose movements had a powerful effect on earthly creatures. To a very great extent, Medieval European Christians inherited this perspective.
To many people today, especially those who have had enough of nonsensical Facebook posts about zodiac signs and personality types, the idea that the planets can affect our lives seems ridiculous. As Bailey points out, however, it is actually quite intuitive:
“That astral bodies imparted energies that could influence terrestrial ones was hardly an outlandish idea—one had only to note how the moon influenced tides or more basically how the rising sun warmed the air to be convinced of this fact. That the planet Mars could impart martial energies or that the power of Venus somehow facilitated amorous attraction or sexual fertility was widely accepted in the Middle Ages, and much more serious intellectual effort was spent working out exactly how these various forces operated. Although learned astrologers sometimes made predictions about the future, they would hardly have considered themselves diviners or magicians. Rather, they would have presented themselves as wise men and philosophers exploring the forces of nature.”
In addition to tidal forces and solar heat, I would also add that skeptics should ask a nurse about working during a full moon.
As Medievals tangled with the precise workings of the influence of the stars on earthly life, they were quick to note that this influence was not direct. Lewis in The Discarded Image has an excellent passage on this:
“In accordance with the principle of devolution or mediation the influences do not work upon us directly, but by first modifying the air. As Donne says in The Exstasie, ‘On man heaven’s influence works not so But first it imprints the air.’ A pestilence is caused originally by malefical conjunctions of planets, as when
Kinde herde tho Conscience and cam out of the planetes And sente forth his forayers, fevers and fluxes.
(Piers Plowman, C. XXIII, 80.)
But the bad influence operates by being literally ‘in the air.’ Hence when a medieval doctor could give no more particular cause for the patient’s condition he attributed it to ‘this influence which is at present in the air.’ If he were an Italian doctor he would doubtless say questa influenza. The profession has retained this useful word ever since.”
That’s right. When you say you have the flu, you’re actually taking part in an old tradition of ascribing airborne maladies to the influence of the planets. You astrologer, you.
So how did we get here? Clearly the Church no longer regards astrology as kosher. How did this happen?
The answer is partly that the Church always had certain objections to astrology, or at least to the abuse of it. Lewis outlines three of these objection:
“(1) Against the lucrative, and politically undesirable, practice of astrologically grounded predictions.
(2) Against astrological determinism…
(3) Against practices that might seem to imply or encourage the worship of planets—they had, after all, been the hardiest of all the Pagan gods.”
Of these three objections, it was the second that caused the most debate among Medieval philosophers and theologians. Lewis devotes more room to this problem than either of the others, and Bailey concurs in regarding it as a highly problematic issue:
“The difficulty lay in rescuing some acceptable systems of astrology from the condemnations of earlier authorities, and from the dilemma that the determinative power of astrological forces seemed to conflict with the important Christian notion of human free will.”
Christianity presents a notion of human responsibility, and an emphasis on moral decision-making, that seems reliant on some notion of free will. After all, if King David was compelled to sin with Bathsheba due to the lascivious influences of Venus, how can he be held accountable for his actions? How can Abraham be praised for his faithfulness when it was merely the stars that decreed his actions?
Here Christian theology and Medieval science appeared to be in conflict, and it took centuries to work out something like an acceptable solution. Bailey points to Albertus Magnus (c.1200-1280) as the first to propose this solution, but it was his pupil, Thomas Aquinas (1225-1274), who explained it as part of his masterful theological system which determined the course of the rest of Medieval European thought. It is to Aquinas we will turn in the next section, exploring the Medieval solution to this conundrum.
Free Will and the Stars
In order to understand Aquinas’s explanation, we have to place ourselves in the Medieval mindset. To begin with, the distinction between material bodies and immaterial “intellectual substances” is important. In his Compendium of Theology¸ Aquinas begins his explanation of the influence with the stars by acknowledging the way higher bodies impact lower bodies:
“Among intellectual substances, therefore, some are divinely governed by others, that is, the lower by the higher. Similarly lower bodies are controlled, in God’s plan, by higher bodies. Hence every movement of lower bodies is caused by the movements of heavenly bodies. Lower bodies acquire forms and species from the influence thus exercised by heavenly bodies, just as the intelligible exemplars of things descend to lower spirits through higher spirits.”
The way intelligible exemplars descend through spirits is not important. What is significant here is the simple acknowledgment that all material objects “lower down,” that is, towards the earth, are moved and shaped by heavenly bodies. The stars, being physical, effect physical things on earth. This might present a problem if one particular thing were not kept in mind:
“Furthermore, impressions left in lower bodies from the impact of heavenly bodies are natural. Therefore, if the operations of the intellect and will resulted from the impression made by heavenly bodies, they would proceed from natural instinct. And so man would not differ in his activity from other animals, which are moved to their actions by natural instinct. And thus free will and deliberation and choice and all perfections of this sort, which distinguish man from other animals, would perish.”
So Aquinas succinctly states the problem: if the stars, through their actions on the physical things of the earth, also control our will and intellect, then we have no free will, no powers of deliberation, and are not to be distinguished from the animals. This is a high-stakes issue. All Biblical anthropology hangs on it.
Before we can take the next step with Aquinas, we have to step deeper into Medieval natural philosophy. Modern Christians tend to have a pretty simplistic explanation of what the soul is and what it does. Medievals had a more complex understanding. After acknowledging that man is a “rational animal,” that is, a living and moving being with the capacity to reason, C. S. Lewis goes on to explain the complexities of the human soul:
“Rational Soul, which gives man his peculiar position, is not the only kind of soul. There are also Sensitive Soul and Vegetable Soul. The powers of Vegetable Soul are nutrition, growth, and propagation. It alone is present in plants. Sensitive Soul, which we find in animals, has these powers but has sentience in addition. It thus includes and goes beyond Vegetable Soul, so that a beast can be said to have two levels of soul, Sensitive and Vegetable, or a double soul, or even—though misleadingly—two souls. Rational Soul similarly includes Vegetable and Sensitive, and adds reason.”
All three kind or levels of soul are immaterial, but each Rational Soul in particular is directly created by an act of God, whereas as lower level souls possessed by animals and plants arise due to the inner workings of natural—though spiritual—forces.
Just as our bodies have particular “faculties,” or abilities, such as a hand being capable of grasping or of punching or of lightly touching, so our souls have different faculties. Lewis goes on to describe two faculties of the rational soul in particular—intellect (intellectus) and reasoning (ratio):
“We are enjoying intellectus when we ‘just see’ a self-evident truth; we are exercising ratio when we proceed step by step to prove a truth which is not self-evident. A cognitive life in which all truth can simply be ‘seen’ would be the life of an intelligentia, an angel. A life of unmitigated ratio where nothing was simply ‘seen’ and all had to be proved, would presumably be impossible; for nothing can be proved if nothing is self-evident. Man’s mental life is spent in laboriously connecting those frequent, but momentary, flashes of intelligentia which constitute intellectus.”
This means that man has both a faculty which completely overleaps sensory input (intellectus), and a faculty which joins these truths together and pushes them in new directions. Both these faculties belong to an immaterial part of man, one directly created by God, and not arising by natural processes. This allows Aquinas to resolve the problem of the effect heavenly bodies have on earthly ones:
“Nevertheless, since the will is not subject to the passions in such a way as necessarily to follow their enticement, but on the contrary has it in its power to repress passions by the judgment of reason, the human will is not subject to impressions emanating from heavenly bodies. It retains free judgment either to follow or to resist their attractions, as may seem to it expedient.”
Thus, while man’s powers of growth, nutrition, and propagation may be effected by the heavenly bodies, or even his ability to sense the world around him, his will remains free. There is a rational core within man capable of resisting and even contradicting the influence of the heavenly bodies. Of course, not everyone has the strength of character to pull this off:
“Only the wise act thus; the masses follow the lead of bodily passions and urgings. For they are wanting in wisdom and virtue.”
This has two important implications. First, astrology will still by and large be effective in predicting the general behavior of masses of humanity, even if it is not always accurate in predicting the actions of individual humans. Second, it is necessary to cultivate both wisdom and virtue to obtain true freedom from the forces of the world around you. Education, in the deeper sense of the term, is important.
The Legacy of the Solution
Aquinas, following in his teacher’s footsteps, provided a very sensible solution to the theological problem presented by the notion of astrological determinism. But while it may seem sensible, it was by no means universally accepted:
“Yet for various reasons this solution was not entirely successful. Doubts remained about the exact nature and extent of astral influence, and some authorities denied such influence altogether. The very skeptical theologian and natural philosopher Nicholas Oresme (ca. 1325-1382), for example, maintained that the astral bodies projected no forces toward the earth aside from light and heat.”
In the centuries that followed, the discussion faded into obscurity. One the one hand, the issue of determinism was being fought over by Reformed theologians and Remonstrants who were much more concerned with salvation than the stars. On the other, the Copernican revolution so thoroughly altered our understanding of the structure of the solar system that the old explanations for the stars influenced the earth no longer applied. Both the theological and the scientific halves of the conundrum drifted apart into new contexts.
This calls into question just why we still object to astrology. It seems that the most obvious answer is simply that we believe it is unsupported by science. Modern natural philosophers have called the notion superstitious, and Christians have agreed with them, lumping the once respectable discipline in with tarot cards and palmistry. This objection, while perhaps more definitive, is far less interesting.
The beautiful thing about the theological conundrum that astrology presented was that it forced Christians to show how theology and science were related. For Medievals, these were not hugely divided disciplines which would never ordinarily interact. The world the Bible described and the world natural philosophy described were one in the same, and so theological issues were in fact very likely to have an impact on scientific views, and vice versa.
That, I think, is a sense of unity worth recovering—the idea that the God who made the heavens is the same God who was incarnate in the person of Jesus Christ, and so the truths of His world and the truths of his Word are not separate from one another. Perhaps it is good that the problem of astrological determinism died, but it also exactly the sort of theological-scientific problem we should expect to see in God’s universe.
 Michael D. Bailey, Magic and Superstition in Europe, pgs. 93-94.
 C. S. Lewis, The Discarded Image. (2009 printing from Cambridge University Press.) pg. 110.
 Lewis, pgs. 103-104.
 Bailey, pg. 98.
 Bailey, pg. 98.
 Thomas Aquinas, Compendium of Theology, translated by Cyril Vollert, with New Introduction by Richard Munkelt. Angelico Press. Pg. 133/chapter 127.
 Aquinas, pg. 134/chapter 127.
 Lewis, pg. 153.
 Lewis, pg. 154.
 Lewis, pg. 157.
 Aquinas, pg. 135.
 Aquinas, pg. 135.
 Bailey, pg. 98.