Ptolemys Tetrabiblos - Ch. 2
KNOWLEDGE MAY BE ACQUIRED BY ASTRONOMY TO A CERTAIN EXTENT

THAT a certain power, derived from the æthereal nature, is diffused over and pervades the whole atmosphere of the earth, is clearly evident to all men. Fire and air, the first of the sublunary elements, are encompassed and altered by the motions of the æther. These elements in their turn encompass all inferior matter, and vary it as they themselves are varied; acting on earth and water, on plants and animals. 1

The Sun, always acting in connection with the Ambient, contributes to the regulation of all earthly things: not only by the revolution of the seasons does he bring to perfection the embryo of animals, the buds of plants, the spring of waters, and the alteration of bodies, but by his daily progress also he operates other changes in light, heat, moisture, dryness and cold; dependent upon his situation with regard to the zenith.

The Moon, being of all the heavenly bodies the nearest to the Earth, also dispenses much influence; and things animate and inanimate sympathize and vary with her. By the changes of her illumination, rivers swell and are reduced; the tides of the sea are ruled by her risings and settings; and plants and animals are expanded or collapsed, if not entirely at least partially, as she waxes or wanes.

The stars likewise (as well the fixed stars as the planets), in performing their revolutions, 1 produce many impressions on the Ambient. They cause heats, winds, and storms, to the influence of which earthly things are conformably subjected.

And, further, the mutual configurations of all these heavenly bodies, by commingling the influence with which each is separately invested, produce a multiplicity of changes. The power of the Sun however predominates, because it is more generally distributed; the others either co-operate with his power or diminish its effect: the Moon more frequently and more plainly performs this at her conjunction, at her first and last quarter, and at her opposition: the stars act also to a similar purpose, but at longer intervals and more obscurely than the Moon; and their operation principally depends upon the mode of their visibility, their occultation and their declination.

From these premises it follows not only that all bodies, which may be already compounded, are subjected to the motion of the stars, but also that the impregnation and growth of the seeds from which all bodies proceed, are framed and moulded by the quality existing in the Ambient at the time of such impregnation and growth. And it is upon this principle that the more observant husbandmen and shepherds are accustomed, by drawing their inferences from the particular breezes which may happen at seed-time and at the impregnation of their cattle, to form predictions as to the quality of the expected produce. In short, however unlearned in the philosophy of nature, these men can foretell, solely by their previous observation, all the more general and usual effects which result from the plainer and more visible configurations of the Sun, Moon, and stars. It is daily seen that even most illiterate persons, with no other aid than their own experienced observation, are capable of predicting events which may be consequent on the more extended influence of the Sun and the more simple order of the Ambient, and which may not be open to variation by any complex configurations of the Moon and stars towards the Sun. There are, moreover, among the brute creation, animals who evidently form prognostication, and use this wonderful instinct at the changes of the several seasons of the year, spring, summer, autumn, and winter; and, also, at the changes of the wind.

In producing the changes of the seasons, the Sun itself is chiefly the operating and visible cause. There are, however, other events which, although they are not indicated in so simple a manner, but dependent on a slight complication of causes in the Ambient, are also foreknown by persons who have applied their observation to that end. Of this kind, are tempests and gales of wind, produced by certain aspects of the Moon, or the fixed stars, towards the Sun, according to their several courses, and the approach of which is usually foreseen by mariners. At the same time, prognostication made by persons of this class must be frequently fallacious, owing to their deficiency in science and their consequent inability to give necessary consideration to the time and place, or to the revolutions of the planets; all which circumstances, when exactly defined and understood, certainly tend towards accurate foreknowledge.

When, therefore, a thorough knowledge of the motions of the stars, and of the Sun and Moon, shall have been acquired, and when the situation of the place, the time, and all the configurations actually existing at that place and time, shall also be duly known; and such knowledge be yet further improved by an acquaintance with the natures of the heavenly bodies--not of what they are composed, but of the effective influences they possess; as, for instance, that heat is the property of the Sun, and moisture of the Moon, and that other peculiar properties respectively appertain to the rest of them;--when all these qualifications for prescience may be possessed by any individual, there seems no obstacle to deprive him of the insight, offered at once by nature and his own judgment, into the effects arising out of the quality of all the various influences compounded together. So that he will thus be competent to predict the peculiar constitution of the atmosphere in every season, as, for instance, with regard to its greater heat or moisture, or other similar qualities; all which may be foreseen by the visible position or configuration of the stars and the Moon towards the Sun.

Since it is thus clearly practicable, by an accurate knowledge of the points above enumerated, to make predictions concerning the proper quality of the seasons, there also seems no impediment to the formation of similar prognostication concerning the destiny and disposition of every human being. For by the constitution of the Ambient, even at
the time of any individual's primary conformation, the general quality of that individual's temperament may be perceived; and the corporeal shape and mental capacity with which the person will be endowed at birth may be pronounced; as well as the favourable and unfavourable events indicated by the state of the Ambient, and liable to attend the individual at certain future periods; since, for instance, an event dependent on one disposition of the Ambient will be advantageous to a particular temperament, and that resulting from another unfavourable and injurious. From these circumstances, and others of similar import, the possibility of prescience is certainly evident.
There are, however, some plausible assailants of this doctrine, whose attacks although greatly misapplied seem yet worthy of the following observations.

In the first place, the science demands the greatest study and a constant attention to a multitude of different points; and as all persons who are but imperfectly practised in it must necessarily commit frequent mistakes, it has been supposed that even such events as have been truly predicted have taken place by chance only, and not from any operative cause in nature. But it should be remembered that these mistakes arise, not from any deficiency or want of power in the science itself, but from the incompetency of unqualified persons who pretend to exercise it. And, besides this, the majority of the persons who set themselves up as professors of this science, avail themselves of its name and credit for the sake of passing off some other mode of divination; by that means defrauding the ignorant, and pretending to foretell many things which from their nature cannot possibly be foreknown; and consequently affording opportunities to more intelligent people to impugn the value even of such predictions as can rationally be made. The reproach, however, thus brought upon the science is wholly unmerited; for it would be equally just to condemn all other branches of philosophy, because each numbers among its professors some mischievous pretenders.

Secondly, it is not attempted to be denied that any individual, although he may have attained to the greatest possible accuracy in the science, must still be liable to frequent error, arising out of the very nature of his undertaking, and from the weakness of his limited capacity in comparison with the magnitude of his object. For the whole theory of the quality of matter is supported by inference rather than by positive and scientific proof; and this is caused principally by the concretion of its temperament out of a multitude of dissimilar ingredients. And, although the former configurations of the planets have been observed to produce certain consequences (which have been adapted to configurations now taking place), and are, after long periods, and in a greater or less degree, resembled by subsequent configurations, yet these subsequent configurations never become exactly similar to those which have preceded them. For an entire return of all the heavenly bodies to the
exact situation in which they have once stood with regard to the earth will never take place, or at least not in any period determinable by human calculation, whatever vain attempts may be made to acquire such unattainable knowledge. 1 The examples referred to for guidance being therefore not exactly similar to the existing cases to which they are now applied, it must naturally follow that predictions are sometimes not borne out by the events. Hence arises the sole difficulty in the consideration of events produced by the Ambient. For no other concurrent cause has been hitherto combined with the motion of the heavenly bodies; although the doctrine of nativities, particularly that part of it relating to peculiar individual temperament, demands also the consideration of other concomitant causes, which are neither trifling nor unimportant, but essentially potent in affecting the individual properties of the creatures born. Thus the variety in seed has the chief influence in supplying the peculiar quality of each species; for, under the same disposition of the Ambient and of the horizon, each various kind of seed prevails in determining the distinct formation of its own proper species; thus man is born, or the horse is foaled; and by the same law are brought forth all the other various creatures and productions of the earth. It is also to be remembered, that considerable variations are caused in all creatures by the respective places where they may be brought forth: for although, under the same disposition of the Ambient, the germs of the future creatures may be of one species, whether human or of the horse, the difference in situation, of the places in which they are generated, produces a dissimilarity in the body and spirit of one from the body and spirit of another: and in addition to this it must be considered that different modes of nurture, and the variety of ranks, manners, and customs, contribute to render the course of life of one individual greatly different from that of another 2; consequently,
unless every one of these varieties be duly blended with the causes arising in the Ambient, the prejudgment of any event will doubtless be very incomplete. For, although the greatest multiplicity of power exists in the Ambient, and although all other things act as concurrent causes in unison with it, and can never claim it as a concurrent cause in subservience to them, there will still, nevertheless, be a great deficiency in predictions attempted to be made by means of the heavenly motions alone, without regard to the other concurrent causes just now adverted to.

Under these circumstances, it would seem judicious neither to deny altogether the practicability of prescience, because prognostications thus imperfectly derived are sometimes liable to be fallacious; nor, on the other hand, to admit that all events, whatever, are open to previous inquiry; as if such inquiry could in all cases be securely conducted without having recourse to mere inference, and as if it were not limited by the narrow extent of mere human abilities. The art of navigation, for instance, is not rejected, although it is in many points incomplete; therefore the bare fact that predictions are frequently imperfect cannot authorise the rejection of the art of prescience: the magnitude of its scope, and the faint resemblance that it bears to a divine attribute, should rather demand grateful commendations, and receive the utmost regard and attention. And, since no weakness is imputed to a physician, because he inquires into the individual habit of his patient, as well as into the nature of the disease, no imputation can justly attach to the professor of prognostication, because he combines the consideration of species, nurture, education and country, with that of the motion of the heavens: for as the physician acts but reasonably, in thus considering the proper constitution of the sick person as well as his disease; so, in forming predictions, it must surely be justifiably allowable to comprehend in that consideration every other thing connected with the subject in addition to the motion of the heavens, and to collect and compare with that motion all other co-operating circumstances arising elsewhere.