In the latest post (( http://heavenastrolabe.net/semiarc-and-alchabitius-directions/ )) we saw as semiarc (or alchabitius, which is another way to collect numbers) fits very well with Ptolemy’s example given in Tetrabiblos III, 10 (( Ptolemy. Tetrabiblos. Translation Frank Robbins. Cambridge Mass. ;London: Harvard University Press ; W. Heinemann, 1980. I’ve used the Italian translation cura Prof. Giuseppe Bezza, unpublished )) . But what about Regiomontanus and “under the pole” directions? Are they different methods? Are they congruent to Ptolemy?
A rapt parallel is the aspect between two points – both rapt by the motion of the Primum Mobile, when they have the same distance from the meridian, which is proportional to their semi-arcs. Differently from the mundane parallel, where one point is fixed on the natal position, and the other moves, here both are directed. (( Martin Gansten, Primary directions: astrology’s old master Technique (The Wessex Astrologer, 2009 especially page 92). ))
Reading here and there I see that primary directions are seen as very difficult and occult. It is not like that.
Ideas which are behind are very easy to grasp, and modern software can do all the calculation for us: on the other hand people who have learned them generally use them as a way to show how clever and expert they are.
As many of us know, Placido Titi did use his own calculation of Part of Fortune, which he took from Adriano Negusanzio “nobleman from Fano, very expert both in the astrological doctrine according the true doctrine of Ptolemy, and in natural science and in the other secrets of nature… “
In his Canon de Parte Fortunae, Placido explains which is the true method and gives an example, showing the goodness of the method with the help of directions.
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):