THEORY OF ASTROLOGICAL PREDICTION
If it be admitted that the heavenly bodies by their position and condition at the time of a person's birth influence or affect his body, vitally, mind and fortune, then it is to be supposed that the subsequent motions of the heavenly bodies would continue to influence and modify those personal powers and characteristics throughout the remainder of the life.
The general theory of astrological prediction is that the natal horoscope contains within itself, like the seeds of a vegetable or the egg of an animal, all the potencies for form, life and intelligence and all the possibilities of fate and fortune that can come to the person in his lifetime.
The particular time when these potencies and possibilities of the natal horoscope may take effect in the life is to be discovered by examining the motions of the heavenly bodies subsequent to birth.
The most obvious system of motion of the heavenly bodies which may be used for prognostication relative to the natal horoscope is that of the transits, as they are called, of the planets that are constantly occurring throughout the life.
At the same time, transits are the most remote from the time of birth and hence are the weakest indications that may be used for prediction.
All other systems of prediction except transits are symbolical in nature and depend upon the principle of correspondences to account for the results.
The system of prediction most commonly used after transits is that of the progressed horoscope, as it is called.
The theory of this system is that of the correspondences between the cycle of the day and the cycle of the year.
The first day after birth the heavenly bodies describe the nature of the heavenly influences throughout the first year of life.
The second day after birth likewise discovers the nature of the second year of life, and so for each year of life there is a corresponding day after birth that may be used as an index to unravel the cause of the changes and events of life.
This system of the progressed horoscope has the advantage over the system of transits that the motions are much nearer in time to the birth, and hence may be considered as more deep-seated in effect.
Nevertheless, these two systems, namely, transits and progressed horoscope, are not to be considered opposed or antagonistic, but rather that they are mutually cooperative toward the one result of a more perfect understanding of the nature, opportunities and manifestation of the individual life and fortune.
The next system after the progressed horoscope is that of equatorial arcs, sometimes called primary arcs, or Placidian arcs.
They are called primary arcs because they measure by arc the first aspects formed by the heavenly bodies with the positions of the significant places of the natal chart.
This system is based on the diurnal motion of the heavens and the approximate time taken for a degree of the celestial equator to pass the meridian is taken to represent a year of life.
The number of degrees required bringing a heavenly point or body into some exact astrological aspect with some other heavenly point or body will indicate a similar number of years after birth as the time when the aspect will become most powerful in the individual's life.
The equatorial arcs that are effective in a life-time are all completed within a few hours after birth.
Hence the system of primary arcs is closer in time to the birth than any other system and can be considered as next in power to the natal horoscope.
Natal astrology has come to modern times from antiquity chiefly through the writings of Claudius Ptolemy, a Greek astronomer and astrologer who lived in the second 'century AD.
In his writings on astrology he devotes a chapter to the explanation and calculation of equatorial arcs, which he calls "modes of prorogation," that is to say in simple language, methods of prediction.
Ptolemy's rather meager outline of modes of prorogation was expanded and fully explained by Placidus di Titus, an Italian monk of the 17th century, who called these modes of prorogation "arcs of direction" which remains the modern designation.
Placidus applied the modern methods of spherical trigonometry to the calculation of the arcs of direction and published his method in a book entitled "Primum Mobile."
In the last decade of the 19th century there was a growing interest in Astrology and the method of the progressed horoscope was largely brought into popular 'use because it was easy of application, requiring only the simplest mathematical calculations and furthermore could be used independently of a knowledge of the exact birth time.
The method of equatorial arcs requires that the birth time should be known to the very minute.
While in the method of the progressed horoscope if a birth time is known to within ten minutes the results are usually satisfactory.
Progression and Direction:
Two closely related systems for timing events or predicting future conditions for a given individual based on the motions of the Earth and other planets in the days following (and sometimes preceding) birth.
In both systems the positions of the planets, Ascendant, and Mid-heaven in the natal chart are moved forward (or backward) in time according to a given formula.
For example, in secondary progressions (sometimes called secondary directions), the system most widely used by modern astrologers, the formula is "a day for a year."
This means that each day following birth is regarded as equivalent to a year in the life of the native, and the positions of the planets on the thirtieth day after birth, for example, as well as the aspects they form with natal planets, are regarded as symbolic of conditions during the thirtieth year.
In primary directions, on the other hand, the formula is "a degree for a year"; that is, a degree of Right Ascension is regarded as equivalent to a year in the life of the native.
According to this system, the number of degrees a planet or point must travel in order to form an exact aspect with a natal planet is translated into years of age in the life of the native.
Progression is based on the actual orbital motions of the planets along the Ecliptic, whereas direction is based on the apparent motions of the planets as a result of the Earth's rotation on its axis.
Thus in progressions, the bodies move at different rates of speed and sometimes in different directions (that is, they can be retrograde), whereas in directions, the bodies move at the same rate of speed and in the same direction.
There are three main types of progressions: secondary, or major, progressions; tertiary progressions; and minor progressions.
These three types represent ratios between the three basic motions of the Earth: its daily rotation on its axis; its annual revolution around the Sun; and its monthly revolution, with the Moon, around their common center of mass, which is about 3,000 miles from the Earth's center-a period of 27.32 days.
In secondary progressions, a day in the ephemeris is considered equivalent to a year of life, a ratio of 1 to about 365. (The exact ratio used by most modern astrologers is 1 to 365.25, based on the solar day.
However, two outstanding technical astrologers of modem times, Cyril Fagan and L. E. Johndro, used the sidereal day, giving a ratio of 1 to 366.25.)
In tertiary progressions, a day in the ephemeris is considered equivalent to a lunar period, a ratio of 1 to 27.32.
In minor progressions, a lunar period is considered equivalent to a year of life, a ratio of 27.32 to 365, or 1 to 13.368.
It will be seen that planets progressed by the secondary method move relatively slowly, yielding fewer aspects than those formed by the faster moving tertiary and minor progressions.
However, those aspects that are formed are generally considered to be more significant, just as transits of the slower moving outer planets are considered more significant than those of the faster moving inner planets.
The method of tertiary progressions was developed in the twentieth century by the German astrologer Edward Troinski. Finally, bodies may be "regressed" as well as progressed.
(Source: Complete Method of Prediction from Genethliac Astrology According to The Western Systems by Robert DeLuce)