CLAUDIUS PTOLEMY:

TETRABIBLOS

OR THE QUADRIPARTITE MATHEMATICAL TREATISE

2. Of the Degree of the Horoscopic Point.

Difficulty often arises with regard to the first and most important fact, that is, the fraction of the hour of the birth; for in general only observation by means of horoscopic astrolabes at the time of birth can for scientific observers give the minute of the hour, while practically all other horoscopic instruments on which the majority of the more careful practitioners rely are frequently capable of error, the solar instruments by the occasional shifting of their positions or of their gnomons, and the water clocks by stoppages and irregularities in the flow of the water from different causes and by mere chance. It would therefore be necessary that an account first be given how one might, by natural and consistent
reasoning, discover the degree of the zodiac which should be rising, given the degree of the known hour nearest the event, which is discovered by the method of ascensions. We must, then, take the syzygy most recently preceding the birth, whether it be a new moon or a full moon; and, likewise having ascertained the degree accurately, of both the luminaries if it is a new moon, and if it is a full moon that of the one of them that is above the earth, we must see what stars rule it at the time of the birth. In general the mode of domination is considered as falling under these live forms: when it is trine, house, exaltation, term, and phase or aspect; that is, whenever the place in question is related in One or several or all of these ways to the star that is to be the ruler. If, then, we discover that One star is familiar with the degree in all or most of these respects, whatever degree this star by accurate reckoning occupies in the sign through which it is passing, we shall judge that the corresponding degree is rising at the time of the nativity in the sign which is found to be closest by the method of ascensions. But if we discover two or more corulers, we shall use the number of degrees shown by whichever of them is, at the time of birth, passing through the degree that is closer to that which is rising according to the ascensions. But if two or more are close in the number of degrees, we shall follow the one, which is most nearly related to the centres and the sect. If, however, the distance of the degree occupied by the ruler from that of the general horoscope is greater than its distance from that of the corresponding mid-heaven, we shall use this same number to constitute the midlevel and thereby establish the other angles.




Ptoletmy's Tetrabiblos

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