The only question is, how far are we able to follow the workings of this general law in individual cases? The perfect astrologer would require a thorough acquaintance with all the infinite detail of nature and the powers of mind and body. Often therefore astrologers can only approximately and not precisely predict what the stars signify. But the science of astrology should not be abused because certain men who call themselves astrologers or physicians but are really diviners and liars err in their judgments. But astrology proper is neither deceitful nor idle, and the astrologer “speaks the truth in most cases and very rarely fails of correct prognostication except in certain particulars.”[2804] Peter’s confidence in astrology despite the complexity of the problems involved reminds one a little of the confidence of the political or social scientist of the present in his methods compared to those of the mere politician or indiscriminate philanthropist.
And not magic.
Again in the first Differentia of the Lucidator Peter argues the question whether astronomy or astrology is a science and meets various arguments raised against the study of the stars.[2805] He holds that, while difficult and laborious, it is noble and honorable, a beautiful discipline adapted to the loftiest intellects, an entirely lawful and licit science. Like Michael Scot, Peter lists and defines various other arts of divination and magic in order to show that the science of the stars is in no way superstitious, as some of them are, and that it neither conjures spirits nor employs exorcisms and suffumigations, as do some arts of divination which try to justify themselves by claiming a connection with the highly reputable science of the stars. Like Guido Bonatti, Peter characterizes as “hypocrites” those who under pretense of defending God’s prerogatives attack judicial astrology as derogating from divine majesty and involving necessity and compulsion. Those who detest such a science should rather be detested themselves, he says, together with those vulgar deceivers and charlatans whom they mistake for astrologers.
Occult virtues from the stars.
Indeed, if the perfect astrologer should know nature and man thoroughly, it is also true in Peter’s opinion that astrology helps one to solve the problems of natural science. “We see,” he writes,[2806] “that precious stones and medicines have marvelous and occult virtues which cannot come from the qualities and natures of the elements (constituting them), since nothing acts beyond its species and every agent produces an effect in matter commensurate with itself.” It is useless to try to argue a priori from the qualities of the constituent elements what these occult properties of particular objects will be; they can be investigated only by experience. And it seems evident to Peter that they can be accounted for only as products of the influence of the stars. Indeed, the same species of plant, grown under a different quarter of the heavens, may acquire new virtues. All inferior objects, he affirms in another chapter,[2807] are filled by the action of those superior bodies with demoniac functions and virtues, so that Aristotle in De coelo et mundo says that some of the ancients held that all these objects are full of gods. An indeed suggestive passage from Aristotle, and more so than Peter of Abano or the Stagirite himself realized, tracing back the conception of occult virtue to its origin in fetishism and animism, whence too the gods sprang!
Astrological medicine.
Peter was convinced that a knowledge of astronomy and astrology was not only valuable but necessary in the practice of medicine. “Those who pursue medicine as they should and who industriously study the writings of their predecessors, these grant that this science of astronomy is not only useful but absolutely essential to medicine.”[2808] Peter cites Hippocrates and Haly in his support and advises the medical practitioner to look up the nativity of the patient, or, if this is impracticable, to address an interrogation on the case to an astrologer. By astronomy one can also foretell changes in the weather and regulate the treatment of the case accordingly. Diet and drink, purgatives and drugs, should all be administered with due regard to the constellations. Two Differentiae[2809] of the Conciliator discuss at length the theme of critical days and their relation to the phases of the moon, which planet, as Peter more than once explains, is assumed to represent the influence of all the others, while to it is especially delegated the control of generation and corruption. The doctor should therefore keep his eye especially upon the moon, a point further emphasized in the pseudo-Hippocratic treatise of astrological medicine which Peter is said to have translated. In still another chapter of the Conciliator[2810] the question at issue is whether blood-letting is preferable in the first or some other quarter of the moon. Surgeons, too, should not operate when the stars are unpropitious and should note the apportionment of the members of the human body among the signs of the zodiac. When the patient’s symptoms are ambiguous, the perplexed doctor may bridge the gap in his medical prognostication by recourse to astrology. This will tend to increase his reputation with his patients who will marvel at his power of prognostication. While thus discussing his tenth question, whether a doctor should know astronomy, Peter adds that astrology is useful in metaphysics as well as in medicine, giving as an example the fact that Aristotle appeals to astrologers at one point of his Metaphysics.
The stars and length of life.
Peter more than once touches upon the influence of the stars upon the length of human life: in Difference 9, for example, where he is inquiring whether men lived longer in ancient times than in his own day; in Difference 21, where the point at issue is whether a temperate “complexion” is more conducive to longevity, and where he indulges in considerable detail about the control of the planets over the process of generation; and in Difference 113, where the question is whether there is any way of putting off natural death. According to the astrologers, one hundred and twenty years—the length of a greater solar year—was the natural term of life, a considerable reduction from the age of the patriarchs of the Old Testament, but much longer than most men lived in Peter’s time. He thinks that the people of India live longer because their climate is subject to Saturn. In Difference 26 Peter divides the life of man into seven ages under the seven planets.
Nativities.