But while he thus rejects incantations and is practically silent on the subject of natural magic, Seneca accepts natural divination in well-nigh all its branches: sacrificial, augury, astrology, and divination from thunder. He believes that whatever is caused is a sign of some future event.[482] Only Seneca holds that every flight of a bird is not caused by a direct act of God, nor the vitals of the victim altered under the axe by divine interference, but that all has been prearranged in a fatal and causal series.[483] He believes that all unusual celestial phenomena are to be looked upon as prodigies and portents. A meteor “as big as the moon appeared when Paulus was engaged in the war against Perseus”; similar portents marked the death of Augustus and execution of Sejanus, and gave warning of the death of Germanicus.[484] But no less truly do the planets in their unvarying courses signify the future. The stars are of divine nature, and we ought to approach the discussion of them with as reverent an air as when with lowered countenance we enter the temples for worship.[485] Not only do the stars influence the upper atmosphere as earth’s exhalations affect the lower, but they announce what is to occur.[486] Seneca employs the statement of Aristotle that comets signify the coming of storms and winds and foul weather to prove that they are stars; and declares that a comet is a portent of bad weather during the ensuing year in the same way that the Chaldeans or astrologers say that a man’s natal star determines the whole course of his life.[487] In fact, Seneca’s chief, if not sole, objection to the Chaldeans or astrologers would seem to be that in their predictions they take only five stars[488] into account. “What? Think you so many thousand stars shine on in vain? What else, indeed, is it which causes those skilled in nativities to err than that they assign us to a few stars, although all those that are above us have a share in the control of our fate? Perhaps those which are nearer direct their influence upon us more closely; perhaps those of more rapid motion look down on us and other animals from more varied aspects. But even those stars that are motionless, or because of their speed keep equal pace with the rest of the universe and seem not to move, are not without rule and dominion over us.”[489] Seneca accepts the theory of Berosus that whenever all the stars are in conjunction in the sign of Cancer there will be a universal conflagration, and a second deluge when they all unite in Capricorn.[490]
Divination from thunder.
It is on thunderbolts as portents of the future that Seneca dwells longest, however.[491] “They give,” he declares, “not signs of this or that event merely, but often announce a whole series of events destined to occur, and that by manifest decrees and ones far clearer than if they were set down in writing.”[492] He will not accept, however, the theory that lightning has such great power that its intervention nullifies any previous and contradictory portents. He insists that divination by other methods is of equal truth, though possibly of minor importance and significance. Next he attempts to explain how the dangers of which we are warned by divination may be averted by prayer, expiation, or sacrifice, and yet the chain of events wrought by destiny not be broken. He maintains that just as we employ the services of doctors to preserve our health, despite any belief we may have in fate, so it is useful to consult a haruspex. Then he goes on to speak of various classifications of thunderbolts according to the nature of the warnings or encouragements which they bring.
Ptolemy.
We pass on from Seneca to a later and greater exponent of natural science and divination, Ptolemy, in the following century. He was perhaps born at Ptolemaïs in Egypt but lived at Alexandria. The exact years of his birth and death are unknown, and very little is recorded of his life or personality. The time when he flourished is sufficiently indicated, however, by the fact that his first recorded astronomical observation was in 127 and his last in 151 A. D. Thus most of his work was probably done during the reigns of Hadrian and Antoninus Pius, but he appears to have lived on into the reign of Marcus Aurelius. His strictly scientific style scorns rhetorical devices and literary felicities, and while it is clear and correct, is dry and impersonal.[493]
His two chief works.
Ptolemy’s two chief works, the Geography in eight books, and ἡ μαθηματικὴ σύνταξις, or Almagest (al-μεγίστη) as the Arabs called it, in thirteen books, have been so often described in histories of mathematics, astronomy, geography, and discovery that such outline of their contents need not be repeated here. The erroneous Ptolemaic theories of a geocentric universe and of an earth’s surface on which dry land preponderated are equally well known. What is more to the point at present is to note that one of these theories was so well fitted to actual scientific observations and the other was thought to be so similarly based, that they stood the test of theory, criticism, and practice for over a thousand years.[494] It should, however, be said that the Geography does not seem to have been translated into Latin until the opening of the fifteenth century,[495] when Jacobus Angelus made a translation for Pope Alexander V, (1409-1410), which is extant in many manuscripts[496] as well as in print.[497] It therefore did not have the influence and fame in the Latin middle ages that the Almagest did or the briefer astrological writings, genuine and spurious, current under Ptolemy’s name.
His mathematical method.
We may briefly state one or two of Ptolemy’s greatest contributions to mathematical and natural science and his probable position in the history of experimental method. Perhaps of greater consequence in the history of science than any one specific thing he did was his continual reliance upon mathematical method both in his astronomy and his geography. In particular may be noted his important contribution to trigonometry in his table of chords, which modern scholars have found correct to five decimal places, and his contribution to the science of cartography by his successful projection of spherical surfaces upon flat maps.
Attitude towards authority and observation.