Principal Question Seven of Chapter Nine
That no astrologer can predict and judge certain things concerning future events
It is asked, in view of what has been said concerning celestial bodies, images, fate, fortune, the ylech, and the alcocoden, whether astrologers can form a certain judgment concerning future events solely by attending to the state of all acting secondary causes.
And it seems that they can, through an argument from the authority of Master Guido Bonatti of Forlì, who says at the beginning of his great book on the judgments of the stars: astronomers judge future events from the stars. And although the stars are innumerable, nevertheless the astronomer himself makes use of them all, since he makes use of the twelve signs under which nearly all the stars are comprised. For this reason he says that more is known about heaven through astrology than about God through theology.
To this it is answered very briefly, without an expenditure of arguments: no.
The reason is that, in order that a certain judgment a priori be made from causal signs, three things are required.
First, the power and state of those signs, with respect to one another or in themselves, must be sufficiently known.
Second, the manner in which such signs or causes are applied to determinate matter must be known beforehand.
Third, the disposition of that matter or patient—whether apt or inapt with respect to the action or influence of such causes or such active power—must be known beforehand.
For example, although a physician knows that a certain medicine is laxative so far as it is concerned, and knows in addition when and how it is applied to Socrates, he still does not thereby know that such an effect, or perhaps its contrary, will follow, if he does not know how the body of Socrates is constituted in its accidental and radical complexion, or intrinsically disposed.
And the case of the astrologer is much more strongly so. For although he knows that, for example, a conjunction of the Sun and Moon is accustomed to produce rain, nevertheless he cannot predict with certainty whether it will rain at a future conjunction—and this for many reasons.
First, because the nature of the planets and of the fixed stars is not sufficiently established: why, in one conjunction and another, different stars are regarded circularly by the conjoined luminaries distinctly according to the three aspects.
Second, because the manner in which that conjunction or its power is applied cannot be known beforehand, nor where it is applied to a greater, better, or worse degree.
Third, even if it were well known to which region it was applied, nevertheless the astrologer would not know whether that region was at that time disposed to the contrary by some accidental mode.
For we see rain occur by the power of one conjunction in one region which at that time is disposed to it accidentally, whether by reason of its location, winds, or complexion; and at that time it does not rain in other regions not so disposed, because the power of such a conjunction is not sufficient to produce rain there.
Ptolemy speaks to this effect in propositions 5 and 17 of the Centiloquium.
And again, even supposing it to be known that the power of a conjunction made in such a sign is directed toward such a region, and that it raises from it vapors sufficient for rain, it nevertheless does not follow that it therefore rains there. For clouds or vapors raised from the sea or from one region are sometimes carried by the winds to another region where there will be rain. And thus there cannot be certainty in this judgment.
Therefore, if an astronomer cannot give or form a certain judgment concerning the most natural and most common effects of the conjunction or opposition of the two great luminaries of heaven—whose nature and influence are the most manifest among all the stars—what and how great is the temerity of wishing to give judgments from other stars, whose natures are known most insufficiently, concerning future effects not only in the elements but also in the powers of the mind and in human moral acts?
Add, moreover, that since divination, prognostication, or the judgment of astrologers concerning future effects in the world, as they admit, depends upon the dispositions, actions, and properties of the fixed and wandering stars, and since no mortal knows their dispositions, actions, and properties, it follows that no sufficiently qualified astrologer can predict and judge certain things concerning future events.
And let us speak of each point.
First, who knows the properties and number of the fixed stars? Certainly, he who knows their names, which are imposed from their properties. And since God alone knows the multitude of the stars and calls them all by name, therefore—and so forth.
For astronomers, as is evident from Part VII of Ptolemy’s Almagest, discovered only 1,022 stars, or places of stars.
And just as there are great and noble stars around the Arctic Pole, so perhaps there are nobler ones around the Antarctic Pole, which is hidden from us, because that part is on the right side of heaven above, which is nobler than the left according to Aristotle. Yet none of those stars is included in that number of 1,022.
The reason is that no one ever saw the stars around the Antarctic Pole, unless perhaps Adam did while he was in the state of innocence. It therefore follows that none of the astronomers can judge with certainty.
Furthermore, who knows why God placed so many fixed stars in the one orb of the eighth sphere, which contains and surrounds the orb of the highest planet, or in what order he placed them: whether they all stand at equal distances from the center of the world, or otherwise?
Whether one stands near the convex surface of that orb, another near its concave surface, and another in the middle of its thickness? Whether they are at equal distances from one another, so that, if they all appeared, they would seem to stand at equal distances from one another?
Or whether they are equal in magnitude according to the truth, although one appears greater than another, as if it were situated lower in the same sphere?
And again, whether their position constitutes certain images—namely, Aries, Taurus, and so forth? And again, whether all the fixed stars are equal?
Therefore, since all these matters concerning the fixed stars are doubtful to mortals, it follows that certain and indubitable knowledge of principles and effects cannot be had from doubtful and poorly known principles.
Likewise, none of the astronomers is yet certain concerning the number of the planets, or wandering or erratic stars, which are said to be seven.
For just as the star Mercury rarely departs so far from the Sun that it can be seen, so perhaps there are some wandering stars or planets which always move invisibly to us beneath the rays of the Sun.
Who, moreover, properly knows the position of the planets? For Ptolemy places the Sun in the middle of the planets, but Geber, the Chaldaean astrologer, says that it is immediately above the Moon.
And although it can also be sufficiently established that the Moon is the lowest of the planets, because it eclipses the Sun, and although there are also some slight congruities and persuasions that Saturn is the highest of the planets and Jupiter immediately beneath it—namely, from slowness of motion and things of this kind—nevertheless no way can sufficiently establish in common the order of position among the planets, which are the Moon, Mercury, Venus, the Sun, Mars, Jupiter, and Saturn: which is above or below another.
Likewise, many doubts remain concerning the movements of the stars around the subterranean Antarctic Pole. On account of this Albategnius said that there can still be some movement in the stars and orbs which no human being has experienced or will experience, as is evident concerning the star which appeared to the three Magi at the time of Christ’s nativity.
From all these things it is apparent that astronomers, who in their judgments trust in the positional order of the planets in their epicycles and eccentric circles, from which they derive their judgments in many cases, cannot give a certain and valid judgment concerning future events, whether natural or voluntary.
This is especially so because in such judgments it is necessary to have regard for the fixed stars, which seem nobler and higher and consequently very powerful with respect to inferior things. Yet, as is clear and was said above, neither are their influences yet established, nor has their number been comprehended, nor can the property of their congregations be known.
Therefore, from all the things which have been said in this ninth chapter, it is sufficiently and clearly apparent how very rarely—and perhaps from a true cause—the lords of astronomy can judge future effects from the stars.
Nor does that reed staff, the support of the ignorance of certain astronomers, protect them when they say indiscriminately of anything which they find among the ancients: “It was experienced thus.”
For Hippocrates, the philosopher most deeply concerned with nature, says: “Life is short, but art long; time is acute, experiment fallacious, judgment difficult.”
Therefore, if it pleases certain kings and princes sometimes to have astronomers, let them keep them and have them for amusement and for instruction in certain universal matters concerning the celestial bodies. But let them in no way trust their judgments in things to be done particularly for themselves or for the commonwealth, abandoning the counsel of prudent men.
The reason is that, although some curious conjectural art concerning future events from the stars can be discovered, nevertheless, on account of the causes stated and many others, it cannot extend to so great a certainty that it can benefit with certainty a particular human being or the commonwealth.
Nor have governors of commonwealths who have been accustomed to trust such persons ever prospered, as can be gathered from ancient histories and many examples.
Now to that vain and superstitious assertion of Guido of Forlì, who says that, although an astrologer does not know the places and influences of all the stars, he nevertheless makes use of them all because he makes use of the twelve signs, under which nearly all the stars are comprised.
It must be answered that, if he takes “sign” for a twelfth part of the Zodiac, he speaks falsely.
But if he takes it for a twelfth part of the starry heaven, which falls between two semicircles meeting at the poles of the Zodiac, I say that this confused use of all the stars in no way suffices for judgments concerning future things. For from those stars which fall in that twelfth part of heaven, a given twelfth part of the Zodiac is said to be of such or such a nature.
But for judgments so particular as Guido himself presumes to give, it is necessary to know whether all the fixed stars regarding from every side some planet situated, for example, in the first degree of Aries would assist or impede it in its action. This cannot be known unless the natures and properties of each of the stars are known, which is impossible for mortals, as was clearly shown above.
And to his statement that more is known about heaven through astrology than about God through theology, it is answered that it is true that more is known about false and superstitious opinions concerning heaven, introduced from every quarter by astrologers, than perhaps can be known by human means concerning true conclusions about the Lord God, revealed by the Holy Spirit for salvation.
These things are Henry of Hesse’s upon Genesis. Let what has been said above concerning the ninth chapter suffice.
Addition
The Lord God revealed concerning divine things only as much as was necessary for our salvation, according to the saying: “These things have been written so that you may believe and, believing, may be saved.” But astrologers have spoken many vain and superfluous—indeed, false—things.