As we saw in these days with Obama’s oath(s) – the first problem for an astrologer is determining the true moment of birth, whatever event we are talking about.
Placidus writes some interesting considerations in his Coelestis Philosophia (1650):
“Sciendum est primo. Because of the difficulty of choosing the true moment of birth, Ptolemy, from the deepest realities of the nature, inferred an excellent method for discovering it, based on the planet which has most rights on the conjunction or opposition of Lights before the birth. In fact this planet, which is the most effective cause, has in itself the faculty of determining the angles in a geniture, and I believe, according natural principles.
It is necessary to know, firstly, that stars with the greatest authority and predominating either in the conjunction or in the opposition of the Lights, having the greatest influence in all the fortnight path of the Moon.
This is because they dispose either both Lights in the New Moon or the one which is above the horizon in the Full Moon. Now, the generation and the corruption of every thing depends firstly and mostly on the Light, as often is told. Therefore Lights produce in the sublunar region effects in agreement with the way they are disposed and impressed, in their union, because of the familiarity with other stars, so they make pregnant of these qualities the elemental region. From this the criterion of the alteration in weather, because Ptolemy talks about it in agreement with this statement.
Secundum sciendum. You should know, secondly, that the effects which are in proximate potency, start to spring and differentiate from causes when they receive a new impulse, even if light or swift. We have experience of this in every moment. It generally happens in fact that a man’s death seems to derive from a cause without any importance, like food or air in the night or cold. These things are not destructive, being of little importance, so they should not been considered as the main causes of the man’s death, but on the contrary, the intrinsic disposition, which, added to the whatever little cause, nevertheless produces a remarkable effect. And this happens very often.
Tertio. Disposition and quality of the predominating planet is effective when that planet beholds the angles of the geniture with whatever familiarity. How many and which are these familiarities and which way we should consider and according which computation and distances from angles, I wrote elsewhere. From all this derives:
Primo. The foundation of the proposed matter: since the fetus in proximate potency manifests himself outside his cause, even a small disposition coming from the planet which is predominating in that moment is sufficient to part the fetus from his cause.
Secundo. Neither degrees or angles should be considered, but some familiarity of the predominating planet in the synod of Lights in respect with some angle in the geniture. We should understand Ptolemy in this way.
Tertio. Benefic and malefic dispositions of Lights in the synod preceding birth influence the fetus very much.”
Let’s give an example of the method taking as our guinea pig the most famous man of the moment, President Barack Obama.
Now let’s cast the chart for preceding syzygy:
It’s a full Moon so we shall take into consideration the Light above the horizon, i.e. the Sun.
We will consider which planet has most rights on the degree of the Sun.
So clearly Saturn at 25 Capricorn is the planet which we should consider in our birth rectification and arrange in some aspect with MC or ASC.
But the familiarities we should consider is “in mundo.”
Gerolamo Vitali writes the same under the headword Amnimodar in his Lexicon Mathematicum Astronomicum Geometricum – 1668
So considering that Placidus would have considered even quintile, sesquiquadrate and biquintile we have:
I should consider Saturn hour distance, which is 4.48 from MC, not far from 4.80 hours of quintile.
Considering that Honolulu is not in the equator, Saturn day temporal hours are less than 15, but exactly 13.5466, we should do the following proportion:
0.32: 15= x:13.5466
x= 0.29 ——> 17 minutes.
So we should move the birth time at 19:07, with an ASC. at 13 Aquarius.
In this case Saturn hour distance is exactly 4.80, so it’s exactly in a familiarity with MC.
Text from Coelestis Philosophia is taken from Giuseppe Bezza, Arcana Mundi: Antologia Del Pensiero Astrologico Antico (Milano: Biblioteca Universale Rizzoli, 1995).
Placidus method is taught by the same Giuseppe Bezza, charts, calculations and mistakes 🙂 by Margherita Fiorello