A statistical study was conducted on an unselected sample of 39 highly intelligent adults. It used their birth data to statistically test whether the sample group was significantly different to the general population with regard to the sample’s mean house strength of the Part of Reasoning as an astrological parameter. The results show the group of highly intelligent adults differs from the general population with respect to this parameter at varying significance levels, depending on the choice of the astrological house system. Significance levels were found to be 0.0053 for the Equal House system and 0.0115 for the Alcabitius House systems. No significant correlation was found between individual IQ scores and house strength of the Part of Reasoning in intelligent adults.
The Part of Reasoning and Eloquence (Pars Rationis in Latin) is one of the few hermetic tools of the traditional astrologer when delineating someone’s horoscope to specifically investigate what we moderns call intelligence. Although there is still controversy about what “intelligence” really is, most people, even academics, would agree that “reasoning” is an essential component of it. Hence the name: The Part of Reasoning! Ancient astrologers seem to have penetrated the gist of the matter by appropriately incorporating the word “reasoning” when naming this intelligence-related astrological significator.
Once a particular natal chart (horoscope) is ready, the Part of Reasoning can be calculated from the zodiacal positions—namely the longitude of the Ascendant, Mercury and Mars—according to the following formulas:

P.R = Ascendant + Mars – Mercury (for diurnal birth)
P.R = Ascendant + Mercury – Mars (for nocturnal birth)

The significance and relation of this Part to intelligence is explained by Guido Bonatti, a famous medieval Italian astrologer, as follows:
Having spoken about the first and second Parts of the Ascendant, we must now speak about its third Part, which is called the Part of Reason and Sense. And since one cannot truly be a human without reason and sense, the sages considered whence they could extract a Part of Reason and Sense. And since they saw that Mercury was naturally the significator of each (also of thoughts and speech and thinking), and Mars was the significator of heat and motion, they extracted from these two a Part which they called the Part of Reason and Sense (this can even be called the Part of Thought and Speech)—which is taken in the day from Mercury to Mars, and in the night the reverse; and it is projected from the Ascendant.
And they said that this Part signifies sense and reason; and it even signifies knowledge and thought and thinking and speaking.

Which if this Part were well disposed in someone’s nativity, and it or the Lord of the domicile in which it is, were with the Lord of the Ascendant, or the Lord of the Ascendant were to aspect [the Lord of the Part] in his own dignity, and Mercury were then to aspect the Part and the Lord of the Ascendant or the Lord of the Part by a trine or sextile aspect (or at least from a square with reception), and Mercury were made fortunate and strong, nor impeded, the native will be rational, knowledgeable, speaking, thinking and perceptive.

And if Mars were then to aspect the Ascendant, or its Lord, or the Lord of the Part, the native will be wise, as I said, and he will have an acute mind, easily learning; and those things which he learned, he will retain well, nor will he be forgetful. [1]

As in any hermetic Part, there are apparently a number of factors that must be taken into consideration and synthesized when delineating this Part. However, based on the general approach regarding the delineation of hermetic parts, one should always start with an examination of the Part’s placement (disposition) in the chart.

House strength serves as a measure to indicate how well a particular planet or Part is posited in a horoscope, so it is one of the most useful variables when assessing the strength, efficiency, and functionality (basically the “well-disposition”) of a Part. As regards hermetic parts, another componential indicator of well-disposition is whether the Part receives aspects from its rulers (dispositors). This is better when the rulers themselves are in good condition. In a traditional approach, a dispositor planet is in good condition only if certain requirements are met. A planet is said to be in good condition if it is strong by house position, fortunate by sign position, and not impeded (afflicted).
Therefore generally speaking, a Part such as this is considered to be “well disposed” if it is strong by house position and/or receives aspects from its rulers, which are preferably in good condition (i.e., strong, fortunate, and unimpeded).
House strength of the Part of Reasoning has been selected in this study as a suitable variable, aside from other things, for its simplicity, as well as the availability of a well-known scoring/ranking system for house strength in astrological tradition.
As far as a particular hermetic/Arabic part is concerned, a strong placement in a chart is the first condition (but by no means the least, because there are always numerous other factors to consider) when hoping to acquire the benefits of that Part. Factual evidence presented here, as well as astrological practice, shows that weak placement of the Part of Reasoning in a particular natal chart does not exclude high, and even very high, intelligence if other conditions (factors) are met that counterbalance the poor placement. For the record, two subjects in the sample with IQs above 145 had their Parts in weak houses (in the 6th and 12th houses by Alcabitius; there were four subjects when using the Equal house system).
In astrology, angular houses are considered strong. These are the 1st, 10th, 7th, and 4th houses in order of decreasing strength. Any planet or Part is said to be strong enough to effectively function for better or worse when located in these houses. Succedent houses (i.e., houses next to the angular houses in a counter clockwise direction) are mediocre by comparison. These are the 11th, 5th, 2nd, and 8th houses in decreasing order of strength. Cadent houses (the 9th, 3rd, 12th, and 6th houses in decreasing order of strength) are weaker still. [2] Of the numerous factors stated in the Part of Reasoning above, only the parameter of “house strength” was taken as a componential measure of well-disposition for the scope of this report. Other factors, including the other elements of well-disposition, not covered here will be the subject of later investigations.
Considering the potential complexity of any individual horoscope, always requiring specific attention on a case-by-case basis, the immense difficulty of relating many astrological significators to intelligence and genius cannot be underestimated. Nevertheless, it is the author’s persistent fantasy to someday be able to predict potential genius and estimate someone’s IQ to within ±10 points (and more accurately, if possible) based on a thorough analysis of their horoscopic significators alone. Crazy as it may sound, given enough accurate birth data and sufficient time and effort, this may be achievable within one or two decades.
Just think of the diagnostic advantages if parents would know an infant’s IQ from the first days after birth, not to mention the great intellectual satisfaction on my part that would come with being able to break the astrological codes and find the hidden patterns behind high cognitive ability!
This article is just a humble first attempt at arriving at what I would like to eventually call astropsychometrics. Just as Hippocrates said about medicine, the same could be said about the art of astrology: Ars longa, vita brevis (Art is long, life is brief).
About the Data and Samples
The sample birth data was collected from 39 voluntary people, mostly active members of high-IQ societies with another person known from private correspondence by e-mail over a period of four years between late 2006 and November 2010.
One subject was disregarded for having an imprecise birth time (reported as “between 2 and 4 pm”), so a reliable computation of the horoscopic house position of the Part of Reasoning would not have been possible. This was necessary because the ascendant and position of the Part of Reasoning, which is derived from the ascendant’s position, are points that are rather sensitive to birth time. For the record, depending on the geographical location, date, and time, the position of the ascendant changes by about 1 degree in the zodiac every 3–5 minutes usually. Such imprecise birth times can still be useful for other analyses that are not time sensitive, for example, the sign positions of planets in the tropical zodiac, because even the fastest celestial body, the Moon, moves only about 1 degree through a sign over 2 hours. So don’t be discouraged from sending birth data if you do not know your precise birth time!
The birth time data at hand is classified as either AA or A for accuracy in the spirit of the Rodden Rating system.[3] The author corrected five of the birth times by matching them to facts and life events of the subjects obtained via private correspondence. The difference between the reported birth times and the corrected birth times were found to be 11 seconds for one subject, eight minutes for another, and one to two minutes for the remaining three people. Although I preferred to use the corrected birth times for these five subjects, the astrological house occupied and associated house strength of the Part of Reasoning did not change, so the findings in this report were not affected at all. One time was taken as 12:30 am without correction because it was reported as being “between midnight and 1 am.”
Of of 39 subjects, 12 were from Mensa and one was from Intertel. All the others were members of high-IQ societies with cut-off levels close to 3 standard deviations, such as EpIQ, and at 3 to 6 (or even greater) standard deviations, such as CIVIQ, HELLIQ, OLYMPIQ, Sigma IV, Camparchimedes, Mega, Platinum, Omega, Homo Universalis, Glia, ISI-S, Pars, and Giga. So the remaining higher part of the sample covers a representative spectrum of 1/500 to 1/1000000000 by rarity and 143 to 190 by minimal IQ score.[4] Thinking that subjects may not be willing to provide their actual IQ scores, they were asked instead to report the name of the high-IQ society with the highest cut-off that they were a member of. So, “IQs” in this report (and possibly in others to come unless otherwise stated), always corresponds to the minimum IQ scores needed by the reported society rather than actual IQ scores. See: http://www.iqsociety.org/?page_id=1012 for a complete list of high IQ societies and their minimum IQ scores (i.e., cut-off IQs) required for admission.
Considering some subjects may have demonstrated higher scores and become members of higher-IQ societies since they initially notified me of their society memberships, I have recently checked the membership lists of the societies that are accessible to me. I noticed that one subject had upgraded his membership from a 3-sigma society to a 4-sigma, so I updated my database accordingly. There may be others I couldn’t verify because membership lists are not always publically published. Thus, the current database used for this report is, to the best of my knowledge, correct and up to date as of 11/19/2010.
All IQ scores used herein and after in calculations are always based on a population standard deviation of 15. Therefore, if a member of a 4-sigma level society sent birth data to me, it was recorded in my database as 160 (based on an SD of 15) rather than 164, which is based on an SD of 16.
Method and Calculations
An astrological software package, Solar Fire v5, was used to cast the horoscopes and determine the positions of the Part of Reasoning. Date of birth, birth time, and place of birth are necessary and sufficient data to cast a horoscope. Modern software often enables the astrologer to access a list of Hermetic/Arabic parts once the chart is cast by inputting the above-mentioned data.
Alcabitius Houses and Equal Houses, along with a 5-degree rule, were employed to determine the house positions of the Part of Reasoning. Associated house strength scores for corresponding house positions of the Part were attributed according to Abraham Ibni Ezra’s system given in Table-A below.[5] These choices were typical of astrologers in the medieval era, which represents the peak in western predictive astrology according to Robert Zoller, one of the contemporary gurus of medieval astrology.
Another very widely appreciated house-division system in traditional astrology, even today, is the whole-sign system. I dismissed this system because previous research and practice by experienced astrologers suggests that it should only be used for topical purposes rather than for assessing the house strength. Often a cadent planet or Part becomes angular in that system, which causes an unjustifiable rise in the strength score.
Table-A. Astrological Houses and House Strength Scores
Strength: 12 6 3 9 7 1 10 5 4 11 8 2
The 5-degree rule, which is commonly used in astrology, requires that a planet or Part be considered to belong to the next house (in terms of strength) when the planet or Part in question is close (within 5 degrees) to the cusp of the next house. As an example, let the cusp of the 7th house be 20 degrees Scorpio and the Part of Reasoning be at 17 degrees Scorpio in the 6th house. The Part is safely regarded to be of the 7th house strength because it is only 3 degrees from the cusp of the 7th house. Some astrologers have objections and some, including me, have reservations when the rule is applied to charts calculated for locations close to the poles, such as Norway and Sweden, where some houses of a particular horoscope can have either very small or very large widths at a given date and time.
The true population mean for house strength was calculated to be 6.5. The calculation is straightforward, especially for the Equal House system where each house, starting from the cusp of the ascendant, is equally spaced by 30 degrees. So for example, if the ascendant is at 12 degrees Taurus in a particular chart, then the next house (i.e., the second house) starts at 12 degrees Gemini, the third house at 12 degrees Cancer, and so on. The likelihood of a planet or Part falling in a particular house by chance in a random chart is always equal to 1/12, because there are 12 houses, and the houses are equally spaced and always occupy 30 degrees each. Therefore, the mean house strength is equal to the arithmetic average of the individual house strength scores given in Table-A above.
The mean house strengths of samples would be expected to distribute normally if the samples were selected at random and the sample size is 30 or more according to statistical theory. The standard deviation of the mean house strength for samples with size n can be estimated from the true population standard deviation of individual house strength values when it is known, or from the sample standard deviation of the house strength, s, by dividing it by the square root of the sample size, n.
The correlation coefficient referred to in this report is Pearson’s r.
A significance level of 0.05 was used as a criterion for testing the null hypothesis because it is widely applied in scientific work.
Significance Test
Null hypothesis: There is no significant difference in terms of the mean house strength of the Part of Reasoning between the general population and the sample consisting of highly intelligent subjects (two thirds of the sample having very high intelligence).
The results of statistical significance tests and pertinent data are summarized below in Table-B.
Interim Conclusions and Discussion
1) Regardless of the medieval house systems selected for determining the house position and associated house strength of the Part of Reasoning, the null hypothesis is rejected based on the finding that corresponding significance values in Test-1 and Test-2, both being one-tail tests, are smaller than the criterion, a = 0.05.
The significance values were found to be 0.012 and 0.0053 for the Alcabitius and Equal house systems respectively. The practical meaning of this is as follows: The probability of obtaining a mean house strength of 7.72 and 7.82 or greater for the Part of Reasoning for a randomly selected sample of 39 highly intelligent subjects by mere coincidence, when the true population mean is 6.5, is about 0.01 or 0.005 depending on if the Alcabitius or Equal House systems is chosen to locate the house occupied and to determine the associated house strength of the Part.
2) There was no significant correlation found between the subjects’ individual IQ scores and the individual house strength of the subjects’ Part of Reasoning. (The minimum correlation required for 39 data pairs to be 95% confident is ±0.31.)
Correlation is suppressed, even ruined, because the IQ data used in calculations are, with a single exception, not the actual IQ scores of the subjects but rather the minimum admission scores of the high-IQ societies they belong to. For example, the IQ scores for the 12 subjects from Mensa were recorded as 130, causing a lack of score variability, although in reality those subjects probably have scores ranging from 130 to 145. Similarly for the rest of the data, the IQs for all subjects who belonged to a 3-sigma level society were recorded as 145 and so on.
The absence of a significant correlation on an individual basis is not a surprise, nor does it hurt the spirit of the matter from an astrological standpoint, because the strong placement of the Part of Reasoning in a particular natal chart is never the single most important parameter to consider as far as intelligence is concerned. In other words, strong placement of the Part in one’s chart is neither truly necessary nor a sufficient condition alone for one to be judged as highly intelligent. Nonetheless, given the choice, it is always good to have this Part strongly placed in one’s chart to fully benefit from the Part’s significations and to compensate for other possible weaknesses.
As a matter of fact, the house strength of the Part as a parameter seems rather to serve to compare the charts of two people, A and B, where A’s Part of Reasoning is stronger by house placement than B’s. Other things being equal, which is never truly achieved in horoscopes except for identical twins, a traditional astrologer would rightfully declare person A to be probably more intelligent than person B.
Given the constraints stated above (e.g., the lack of actual and up-to-date IQ performance data, especially for lower IQs), it is impossible to say if there would be a correlation had the sample comprised not only the intelligent and very intelligent, but all levels of IQ from the true idiot to the extremely intelligent.
The current findings about correlation imply the following: Either there exists no significant correlation at all over the full range of IQs (this needs to also include data about average and even mentally retarded people too) and this has merely manifested itself in a sample consisting of highly intelligent people only, or correlation does not exist only for the intelligent and very intelligent. If the latter is true, this means any possible dependency of IQ on the house strength disappears in the case of very intelligent subjects, and house strength loses its importance and becomes no more than a discriminative factor at high levels of intelligence.
Value of the house strength as a comparative tool, as well as the true meaning of the preceding paragraphs, become more clear when, instead of individual scores, the mean IQ scores and house strengths of the sample and sub-sample are compared (see 3 below).
3) Because n is less than but close to 30 for the sub-sample in Test-3, the significance was estimated by assuming the estimated population standard deviation would remain more or less the same as in Test-2 if n were 30 and the t score (Student’s t) was calculated instead of z. This was done to see how significance would be affected in that case.
The mean IQ of the sub-sample (i.e., the very high IQ group) is greater than the mean IQ of the whole sample by about 9 IQ points. This is accompanied by an appreciable increase in significance (from 0.005 to 0.001) and a 0.45 units increase in the mean house strength.
An increase in significance by an increase in the mean IQ indicates the difference between general population and the sample group consisting of intelligent subjects becomes even more evident when the selected sample consists of the very intelligent subjects only. This means the likelihood of finding people with a weakly placed Part decreases at very high levels of intelligence.
The fact that an increase in the mean IQ is accompanied by an increase in the mean house strength may also imply a latent positive correlation between the two. This requires further analysis of larger data sets representing various levels of IQ segments from 130 to 190 to find out more. Mean IQs, for instance in 10 IQ point increments, between 130 and 190 may reveal whether there is a significant correlation between the mean minimum IQ scores of each segment (such as 130, 140, 150, etc.) and corresponding mean house strengths.
Mean house strength for the sample and sub-sample is around 8. According to Ibni Ezra’s classification, which in fact is nothing more than a useful ranking system, the score of 8 as a measure of strength corresponds to the strength of the 11th house, which is regarded by astrologers as the strongest and most fortunate/favorable house next to the angular houses. Given the findings, it appears to be true in broad sense as regards intelligence too, because on average, very intelligent subjects have at least a moderately strong placement of their Part of Reasoning. This is in close agreement with the theory of traditional astrology, stating that a planet or Part should best be strong (in an angular house), or be at least mediocre by strength (in a succedent house), and not impeded by being in a weak house such as the 6th or 12th house, which are regarded to be the two weakest houses by all astrologers.
Although I do not want to jump to a premature conclusion, it seems these findings justify the reasoning, at least in general terms, of traditional astrologers who would consider the strong placement of a Part as important and the first thing to look for when delineating a Part.
The next update of this report will be when data submissions from intelligent adults reach or exceed 100, with a prospect then to also compare the existing data to those of historical geniuses and eminent intellectuals.
This report would not have been possible without the contribution of birth data from generous friends in the high-IQ community, none of whom I know personally. Special thanks go to Dr. Evangelos Katsioulis for reserving a place in this website to host my work and to Paul Cooijmans and Brennan Martin, who made my project known in the community by linking from their websites.
References and Notes
[1]: The Book of Astronomy, Guido Bonatti, transl. Benjamin Dykes, 2007, Cazimi Press, Vol.II, p.1054
[2]: As far as I know, there is general agreement over the ranking of the houses by strength in the astrological community except for the weakest house. Maybe a majority of astrologers today consider the 12th house as the weakest house, as opposed to Ibni Ezra. Scoring and ranking the houses in terms of strength has its own astro-logics and merits in traditional astrology that will not be dealt with here. Personally I do advocate, albeit tentatively, Ibni Ezra’s choice of the 6th house as the weakest.
[3]: For the Roden Rating system, see: http://www.astro.com/astro-databank/Help:RR
[4]: As a rule, the names of the subjects who submitted birth data are kept confidential unless they gave consent in writing.
[5]: For Ibni Ezra, see: http://www.skyscript.co.uk/ezra.html
(Written by Hakan E.Kayıoğlu)

Hakan E. Kayıoğlu