Very few modern astrologers make use of the parts. The only one normally encountered is the Part of Fortune, and even that appears to be unfamiliar to many. How many more of us place it in our charts but then quietly ignore it in the delineation? I must admit that I was in that group for years! If modern textbooks have little to say about parts, things are very different in ancient and medieval works. They not only devote substantial space to the Part of Fortune, but also use a whole flock of other parts. So where did all the parts go?
The Loss of the Parts
One natural reaction is to say that they were abandoned because they did not work. But that is not necessarily the case: progress in science is neither continuous nor inevitable. We are all familiar with the loss of knowledge after the fall of the Roman Empire, but it does not need hairy, sword-waving barbarians to produce a dark age. Religious fundamentalism largely destroyed learning in the Arab world in the later Middle Ages, and irreligious fundamentalism almost extinguished astrology in 18th century Europe. Few people realise that serious damage was also done in the 16th century. The Renascence is normally seen as a time of progress, which it was, but not without loss. The preoccupation with classical scholarship and the reaction against everything medieval had a narrowing effect especially where the latter sentiment was reinforced by the Reformation.
The spirit of the age led many astrologers to attempt a renascence and reformation in astrology: a return to pre-medieval practice, which they took to be preserved in Ptolemy. But these would-be reformers were mistaken, for the medieval Arabs were actually far closer than Ptolemy to the mainstream of Greek practice. Others, like Cardan, Morin, and Kepler, attempted to recreate astrology as Galileo had recreated physics. Their fault was to have more theories than facts.
All this had implications for the use of parts. The would-be physicists tended to reject parts on the grounds that "there is nothing there". What did they imagine occupied the place of the midheaven? The Ptolemaic school dismissed all parts other than the Part of Fortune as 'Arabic', a misnomer which is still current. As for the Part
of Fortune itself, that (as we shall see shortly) was wrongly calculated and in consequence became gradually abandoned.
The Validity of the Parts
The usual method for finding the Part of Fortune today is that given by Ptolemy: measure from the Sun to the Moon and then add that arc to the ascendant. The original practice confined this method to diurnal charts; at night the arc was measured from the Moon to the Sun. Of all surviving Greek texts, only one agrees with Ptolemy - a single chart cast by an anonymous astrologer a generation before him.  With very few exceptions, medieval astrologers also made the distinction between the nocturnal and diurnal methods, and it survived down to the 18th century.
How can we decide who was right? History would seem to provide a verdict. Ptolemy's method only caught on fifteen centuries after it was introduced, as a result of non-astrological considerations, to be largely abandoned after only a few centuries.
Nevertheless, I have tried to investigate the matter experimentally. Collecting evidence to show whether the parts are valid and, if so, whether they should be calculated differently by day and by night is not as easy as one might think. Looking through collections of nativities, one finds many charts which are not precise enough for us to be sure of the aspects or even the sign of the necessary part. In my investigation I used five parts (Fortune, Spirit, Sickness, Father, and Mother) and for each case I calculated the appropriate part by the traditional formula and a false part by reversing the formula. I then considered both points to see whether their placing in the chart was appropriate.
If the parts were meaningless, both the true and false parts would have no more value than any randomly chosen points: they would be equally effective or ineffective. If the parts were valid, the correctly calculated part would always be suitable and the wrongly calculated part would be either suitable or unsuitable, at random. In that case, the correct part would be more appropriate or at least as good as the false one, but never worse. The latter was the result which I obtained, validating both the parts tested and the method of calculation.
The Nature of the Parts
So what are the parts? The Part of Fortune () is a means of evaluating the relation of the lights and their house positions. The formula by day is:
= Asc + Moon - Sun
But why is the method reversed by night? And is that always the case? In traditional astrology, the difference between diurnal and nocturnal charts is considered fundamental and it affects many considerations. Thus the planets are divided on this basis into two sects:
Diurnal: Sun, Jupiter, Saturn, Mercury as a morning star
Nocturnal: Moon, Mars, Venus, Mercury as evening star
This means that the Sun predominates in diurnal charts, whereas the Moon predominates in nocturnal ones. In the first case we measure the arc for the Part of Fortune from the Sun, in the second from the Moon. The reversed method does have a significance, but as a different part (whose existence explains why the Ptolemaic method sometimes seems to work):
Part of the Spirit (
) = Asc + Sun - Moon
The Part of the Spirit is the reverse of the Part of Fortune in meaning as well as in method: spiritual well-being is opposed to worldly success.
Other planets can be used for other purposes, as shown in the accompanying list. Thus the Part of the Father is found from the Sun and Saturn because they are held to signify the father. Ill health is indicated by the malefics, so they are used to calculate the Part of Sickness. The usual rule is to measure from the diurnal planet by day and from the nocturnal one by night. For the Part of the Father, we measure from the Sun by day because the Sun is then strongest, although Saturn is also a diurnal planet. In the case of the Part of Marriage, we measure from the masculine planet for a man and from the feminine one for a woman. Some parts are always found in the same way and it is not clear as to why this is so. There are also differences in practice between astrologers in the way certain parts are found. Such matters should not be seen as serious problems: rather, as encouragement to further research, taking advantage of the greater number of accurate charts now available.
The use of the parts is essentially as a secondary indication. Nothing can be predicted from a part taken alone: its function is to shed more light on the usual significators. One cannot say that the native is fortunate because the Part of Fortune is well placed and well aspected, unless the Sun and Moon are also strong and free from affliction. On the other hand, favourable lights are of limited use if the Part of Fortune is afflicted. Charles Carter summed this up when he said the parts indicate "actual precipitation as distinct from propensity".
A part is evaluated by considering firstly, the condition of its ruler; secondly, the aspects that it receives, particularly from the significators from which it was found or from its ruler; and thirdly, its house position.
The Parts in Action
A good example of the falsity of Ptolemy's method is seen in the chart of W.B. Yeats. The Part of Fortune is angular and in conjunction with Mercury, the almuten (i.e. the most dignified planet in the chart). Ptolemy would have placed it at 29° Scorpio, in square to the Sun, Jupiter, and Uranus - hardly an indication of success. That position is much more appropriate to the Part of the Spirit, fitting Yeats's restless search for spiritual truth and the inner tensions revealed in his poetry:
"The work is done", grown old he thought,
"According to my boyish plan.
Let the fools rage, I swerved in naught, Something to perfection brought."
But louder sang that ghost, "What then?"
This nativity has many indications of great success. Four planets are in their exaltations or domiciles. The lights are well aspected and in trine to each other. The Moon, light of the sect, is angular. The fixed star Antares is culminating. Mercury, triplicity ruler of the lights and ascendant, is angular and almuten. The second triplicity ruler, Saturn, also the dispositor of the ascendant, is exalted. But there ale also problems: the Sun is peregrine, Mercury is unaspected, and Saturn is in the 8th. The Part of Fortune confirms the positive tendency of the chart.
Another example of a contrast between the parts of Fortune and of the Spirit is found in the nativity of Marilyn Monroe. The Part of Fortune is in sextile to the Moon, in conjunction with Venus, and trine Neptune. This shows her success, founded on the ability to project an almost mythical femininity. Not unexpectedly, in view of her tragic life, the Part of the Spirit is much less favourably placed, being in opposition to the Sun. The Sun, both light of the sect and ruler of the ascendant (by sign and triplicity), is peregrine, at the Uranus/Neptune midpoint, and has the peregrine Saturn as his first triplicity ruler. On the other hand, he is in conjunction with Mercury, his dispositor and the almuten of the chart, and Saturn is at least angular. The parts of Fortune and of the Spirit clearly help to show where the good and bad features will manifest. A major factor in Monroe's life was the separation from her mother, due to the latter's insanity. The problems of her mother are indicated by the afflicted Moon - square Mars and opposition Neptune - and the weak MC - ruled by Venus, peregrine and in her detriment. The impact is made clear by the placing of the Part of the Mother in opposition to the Part of the Spirit.
Other examples of the failure of Ptolemy's methods in nocturnal charts are Mozart and Churchill. Mozart suffered from frequent ill-health and the Part of Sickness was in Aries, ruled by Mars in his fall. By Ptolemy's method however, the part would have been in Aquarius, ruled by Saturn in his domicile. Churchill's father was distant and critical, and died, insane, of syphilis while his son was still in his teens. The normal method puts the Part of the Father in square to Neptune: Ptolemy's puts it in conjunction with the Sun.
The value of the parts in clarifying an interpretation is shown by the nativity of the Prince of Wales. The indications for the 7th house are mixed. The cusp is squared by the Moon, but its ruler, Saturn, is part of a grand trine and in his triplicity. Venus is dignified and in sextile to Mars, but the conjunction with Neptune could cause problems. If we consider the Part of Marriage, at 16° Virgo, we see that the case is worse than it first appears. The part is ruled by Mercury, the one peregrine planet in the chart and it falls on the Venus/Pluto midpoint.
When a birth takes place near to sunrise or sunset, the parts can be an aid to rectification. John Lennon's reported birth time gives the Sun just below the 7th cusp. If the birth was indeed after sunset, the Part of Fortune was in conjunction with the MC and in sextile to the Moon. A diurnal birth would have placed the part in opposition to the Moon and in conjunction with Pluto. The latter position is less appropriate to his worldly success, but far more suitable for the Part of the Spirit, the dependency indicated by the Moon-Pluto opposition manifesting in 'guru' chasing.
Lastly, let's look at the chart of Madonna. Mercury, almuten of the chart and ruler of the ascendant, is rising. The Sun has essential dignity and good aspects. The Part of Fortune, angular and ruled by the almuten, confirms the career success shown in the rest of the chart. Problems under the surface are indicated by the Sun's placement in the 12th house, averse to the Moon, and on the Uranus/Pluto midpoint. Problems appear above the surface when we look at her love life. Venus has no aspect to Mars, never a good sign, and is both peregrine and afflicted. The 7th house planets fill out the picture: the Jupiter-Venus square is well known for numerous affairs. The Part of Marriage confirms all this by falling in the fifth and being squared by Jupiter.
These examples have all been drawn from natal astrology, but the parts were also extensively used in horary charts. The Arabs also developed parts for use in solar ingress, and eclipse charts to assist in economic and political forecasting.
Notes & References:
||Chart 81 in Greek Horoscopes; O. Neugebaur & H.B. Van Hoesen (Am. Phil. Soc., 1959)
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||C.E.O. Carter, 'The Part of Uranus', Astrology, Vol. 47, No.4 (Winter 1973)
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© David McCann. This article is extracted from that first published in The Traditional Astrologer Magazine, Ascella Publications, issue 9, Summer 1995, pp.22-25. Reproduced online December 2004