Whereas there is so little to suggest a belief in astrology in most of Galen’s works, we find among them two devoted especially to astrological medicine, namely, a treatise on critical days in which the influence of the moon upon disease is assumed, and the Prognostication of Disease by Astrology. In the latter he states that the Stoics favored astrology, that Diodes Carystius represented the ancients as employing the course of the moon in prognostications, and that, if Hippocrates said that physicians should know physiognomy, they ought much more to learn astrology, of which physiognomy is but a part.[842] There follows a statement of the influence of the moon in each sign of the zodiac and in its relations to the other planets.[843] On this basis is foretold what diseases a man will have, what medical treatment to apply, whether the patient will die or not, and if so in how many days. This treatise is the same as that ascribed in many medieval manuscripts to Hippocrates and translated into Latin by both William of Moerbeke and Peter of Abano.
Critical days.
The treatise on critical days discusses them not by reason or dogma, lest sophists befog the plain facts, but solely, we are told, upon the basis of clear experience.[844] Having premised that “we receive the force of all the stars above,”[845] the author presents indications of the especially great influence of sun and moon. The latter he regards not as superior to the other planets in power, but as especially governing the earth because of its nearness.[846] He then discusses the moon’s phases, holding that it causes great changes in the air, rules conceptions and birth, and “all beginnings of actions.”[847] Its relations to the other planets and to the signs of the zodiac are also considered and much astrological technical detail is introduced.[848] But the Pythagorean theory that the numbers of the critical days are themselves the cause of their significance in medicine is ridiculed, as is the doctrine that odd numbers are masculine and even numbers feminine.[849] Later the author also ridicules those who talk of seven Pleiades and seven stars in either Bear and the seven gates of Thebes or seven mouths of the Nile.[850] Thus he will not accept the doctrine of perfect or magic numbers along with his astrological theory. Much of this rather long treatise is devoted to a discussion of the duration of a moon, and it is shown that one of the moon’s quarters is not exactly seven days in length and that the fractions affect the incidence of the critical days.
On the history of philosophy.
A treatise on the history of philosophy, which is marked “spurious” in Kühn’s edition, I have also discovered among the essays of Plutarch where, too, it is classed as spurious.[851] In some ways it is suggestive of the middle ages. After an account of the history of Greek philosophy somewhat in the style of the brief reviews of the same to be found in the church fathers, it adds a sketch of the universe and natural phenomena not dissimilar to some medieval treatises of like scope. There are chapters on the universe, God, the sky, the stars, the sun, the moon, the magnus annus, the earth, the sea, the Nile, the senses, vision and mirrors, hearing, smell and taste, the voice, the soul, breathing, the processes of generation, and so on.
Divination and demons.
In discussing divination[852] the treatise states that Plato and the Stoics attributed it to God and to divinity of the spirit in ecstasy, or to interpretation of dreams or astrology or augury. Xenophanes and Epicurus denied it entirely. Pythagoras admitted only divination by haruspices or by sacrifice. Aristotle and Dicaearchus admit only divination by enthusiasm and by dreams. For although they deny that the human soul is immortal, they think that there is something divine about it. Herophilus said that dreams sent by God must come true. Other dreams are natural, when the mind forms images of things useful to it or about to happen to it. Still others are fortuitous or mere reflections of our desires. The treatise also takes up the subject of heroes and demons.[853] Epicurus denied the existence of either, but Thales, Plato, Pythagoras, and the Stoics agree that demons are natural substances, while heroes are souls separate from bodies, and are good or bad according to the lives of the men who lived in those bodies.
Celestial bodies.
The treatise also gives the opinions of various Greek philosophers on the question whether the universe or its component spheres are either animals or animated. Fate is defined on the authority of Heracleitus as “the heavenly body, the seed of the genesis of all things.”[854] The question is asked why babies born after seven months live, while those born after eight months die.[855] On the other hand, a very brief discussion of how the stars prognosticate does not go into particulars beyond their indication of seasons and weather, and even this Anaximenes ascribed to the effect of the sun alone.[856] Philolaus the Pythagorean is quoted concerning some lunar water about the stars[857] which reminds one of the waters above the firmament in the first chapter of Genesis.