The second book begins by distinguishing prediction of events for whole regions or countries, such as wars, pestilences, famines, earthquakes, winds, drought, and weather, from the prediction of events in the lives of individuals. Ptolemy holds that events which affect large areas or whole peoples and cities are produced by greater and more valid causes than are the acts of individual men, and also that in order to predict aright concerning the individual it is necessary to know his region and nationality. He characterizes the inhabitants of the three great climatic zones,[515] quarters the inhabited world into Europe, Libya, and two parts for Asia in the style of the T maps, and subdivides these into different countries whose peoples are described, including such races as the Amazons. The effects of the stars vary according to time as well as place, so that the period in which any individual lives is as important to take into account as his nationality. Ptolemy also discusses how the heavenly bodies influence the genus of events, a matter which depends largely upon the signs of the zodiac, and also how they determine their quality, good or bad, and species, which depends on the dominant stars and their conjunctions. Consequently he gives a list of the things which belong under the rule of each planet. The remainder of the second book is concerned chiefly with prediction of wind and weather through the year and with other meteorological phenomena such as comets.
Nativities.
The last two books take up the prediction of events in the lives of individuals from the stars, in other words the science of nativities or genethlialogy. The third book discusses conception and birth, how to take the horoscope—Ptolemy insists that the astrolabe is the only reliable instrument for determining the exact time; sun-dials or water-clocks will not do—and how to predict concerning parents, brothers and sisters, sex, twins, monstrous births, length of life, the physical constitution of the child born and what accidents and diseases may befall it, and finally concerning mental traits and defects. The fourth book deals less with the nature of the individual and more with the prediction of external events which befall the individual: honors, office, marriage, offspring, slaves, travel, and the sort of death that he will die. Ptolemy in opening the fourth book makes the distinction that, while in the third book he treated of matters antecedent to birth or immediately related to birth or which concern the temperament of the individual, now he will deal with those external to the body and which happen to the individual from without. But of course it is difficult to maintain such a distinction with entire consistency.
Future influence of the Tetrabiblos.
The great influence of the Tetrabiblos is shown not only in medieval Arabic commentaries and Latin translations, but more immediately in the astrological writings of the declining Roman Empire, when such astrologers as Hephaestion of Thebes,[516] Paul of Alexandria, and Julius Firmicus Maternus cite it as a leading authoritative work. Only the opponents of astrology appear to have remained ignorant of the Tetrabiblos, continuing to make criticisms of the art which do not apply to Ptolemy’s presentation of it or which had been specifically answered by him. Thus Sextus Empiricus, attacking astrology about 200 A. D., does not mention the Tetrabiblos and some of the Christian critics of astrology apparently had not read it. Whether the Neo-Platonists, Porphyry and Proclus, wrote an introduction to and commentary upon it is disputed.
CHAPTER IV
GALEN
I. The Man and His Times
Recent ignorance of Galen—His voluminous works—The manuscript tradition of his works—His vivid personality—Birth and parentage—Education in philosophy and medicine—First visit to Rome—Relations with the emperors; later life—His unfavorable picture of the learned world—Corruption of the medical profession—Lack of real search for truth—Poor doctors and medical students—Medical discovery in his time—The drug trade—The imperial stores—Galen’s private supply of drugs—Mediterranean commerce—Frauds of dealers in wild beasts—Galen’s ideal of anonymity—The ancient book trade—Falsification and mistakes in manuscripts—Galen as a historical source—Ancient slavery—Social life; food and wine—Allusions to Judaism and Christianity—Galen’s monotheism—Christian readers of Galen.
II. His Medicine and Experimental Science
Four elements and four qualities—His criticism of atomism—Application of the theory of four qualities in medicine—His therapeutics obsolete—Some of his medical notions—Two of his cases—His power of rapid observation and inference—His happy guesses—Tendency toward scientific measurement—Psychological tests with the pulse—Galen’s anatomy and physiology—Experiments in dissection—Did he ever dissect human bodies?—Dissection of animals—Surgical operations—Galen’s argument from design—Queries concerning the soul—No supernatural force in medicine—Galen’s experimental instinct—His attitude toward authorities—Adverse criticism of past writers—His estimate of Dioscorides—Galen’s dogmatism; logic and experience—His account of the Empirics—How the Empirics might have criticized Galen—Galen’s standard of reason and experience—Simples knowable only through experience—Experience and food science—Experience and compounds—Suggestions of experimental method—Difficulty of medical experiment—Empirical remedies—Galen’s influence upon medieval experiment—His more general medieval influence.