[As always, I couldn't have written this article had I not been blessed by having the privilege of studying under the tutelage of Hart de Fouw, a true Vedic master.]
Perhaps one of the greatest advances in Vedic astrology in the 20th century was the work of an Indian Jyotishi called Sheshadri Iyer. After extensive study of the classical texts, he pioneered a powerful method of prediction, working with divisional charts.
The centerpiece of Iyers' analytical method is the premise that the location by house of the Dasha lord is the most important factor in determining how well the Dasha goes for each sub-chart's themes.
In order to evaluate whether a planet is positively or negatively placed by house, two principles need to be taken into account:
1. There are six pairs of houses, as indicated in the diagram below, wherein if there is a planet is in both of the paired houses, a different set of rules applies than if a planet is in one of the paired houses and the other house is empty.
In other words, if there is are planets in both the 1st and the 7th houses, or in both the 2nd and 12th houses, or in both the 3rd and 11th houses, or in both the 4th and 10th houses, or in both the 5th and 9th houses, or in both the 6th and 8th houses in any divisional chart then a Sankhya Yoga exists between those planets.
Paired Houses of the Sankhya Yoga
If there are planets in both of the paired houses, then one of three types of Sankhya Yogas is formed:
A. Shubha SankhyaYoga. This yoga is formed when the planets in both of the paired houses are natural benefics (i.e. the Moon, Mercury, Venus, or Jupiter). When the Dasha of a planet in a Shubha Sankhya Yogas in a specific divisional chart runs, the theme of that divisional chart goes well.
B. Papa Sankhya Yoga. If the planets in both of the paired houses are natural malefics (Sun, Mars, Saturn, Rahu, or Ketu), then the Dasha of each planet in the Papa Sankhya Yoga goes very badly for the themes of the divisional chart.
C. Mishra Sankhya Yoga. If in one of the paired houses there is only one or more benefic planets, and in the other paired house there is only one or more malefic planets, then a Mishra Sankhya Yoga is formed. The Dasha of the benefic(s) will go well, and the Dasha of the malefic(s) will go poorly for the theme of the divisional chart.
Note: one exception to the above rules is if the Moon is in one of the paired houses and the Sun is in the other paired house, both Dashas go well.
Question: What if there are both benefics and malefics on both sides of a set of paired houses?
Answer: Then the benefics in each of the paired houses form a Shubha Sankhya Yoga with each other, and the malefics on each side form a Papa Sankhya Yoga with each other. I.e. the Dashas of the benefics will go well, and of the malefics poorly.
In the Navamsha chart above, for Percy Bysshe Shelley, Jupiter and Venus form Shubha Sankhya Yogas with each other, and both the Jupiter Dasha and the Venus Dasha will go well for relationship themes (Navamsha chart). Mars and the Sun, on the other hand, form a Papa Sankhya Yoga together, and so both the Mars Dasha and the Sun Dasha will go poorly for relationship themes.
By the way, in the above example, Saturn and the Moon form a Mishra Sankhya Yoga, so the Moon Dasha goes well for relationship and the Saturn Dasha goes poorly for relationship.
Note: as has been said in other articles, the term "go well" means that in general the themes of the divisional chart will flow smoothly. "Go poorly" on the other hand, can mean -- for the Navamsha, for example -- that there might be conflict with a spouse, or the absence of the spouse, or the spouse themselves may be struggling with an issue (e.g. a health, financial, parental, educational, or other issue). In other words, the "space" of the partner is disturbed in some way.
In Jackie O's chart above, Jupiter and Moon form a Shubha Sankhya Yoga, so marriage goes well during Jupiter and Moon Dashas. Her Saturn, on the other hand, forms a Mishra Sankhya Yoga with Jupiter, so its Dasha goes poorly for relationship.
Good and Bad House Placement.
2. Only if the planet under consideration does not form a Sankhya Yoga in a specific divisional chart -- i.e. if there is no planet in the paired house from it -- does a second principle get applied:
A. For planets in good houses in a particular divisional chart, their Dasha goes well for the themes of that sub-chart. Good houses are 1, 4, 5, 7, 9 & 10.
B. For planets in bad houses in a specific divisional chart, their Dashas go poorly for the themes of that sub-chart. Bad Houses are 3, 6, 8 & 12. Also, planets in houses 3 & 8 in a sub-chart indicate the ending of the sub-chart's theme during their Dasha. E.g. The Dasha lord in the 8th house of the Navamsha can indicate the end of a relationship.
c. For planets in neutral houses in a specific divisional chart, their Dashas go mildly well for the themes of that sub-chart, unless they are primarily aspected by malefics and/or their sole enemy (in which case things go poorly). The neutral houses are 2 & 11.
3. Additional important considerations.
There are several factors that can modify or even reverse the above two general methods of prediction. These can be seen as "exceptions to the rule".
A. If a strong Jupiter is conjunct or aspects planets in a D-chart, Jupiter will make the Dashas of the aspected planet(s) go well (or at least better than otherwise). If Jupiter is debilitated (in Capricorn) it does not have the necessary strength, and Jupiter cannot "lift up" the planet it is sole enemy of, Venus; in fact, the aspect of a strong Jupiter on Venus in a sub-chart is detrimental to the themes of the sub-chart during the Venus Dasha.
(Jupiter is strong in any D-chart if it's in its own sign, exalted, with dig bala (in the First House, or in the same sign as in the birth chart (Vargottama).)
Note: A Venus with two or more strengths can also have this uplifting effect.
B. If Mars is in the 6th house in a D-chart and Mars is strong (own sign, exalted, Vargottama) and there is no planet in the 8th house, the Mars Dasha goes well for the themes of that divisional chart.
C. Sole enemies. Each planet has a sole enemy, which acts like a very strong malefic for the planet. If the sole enemy is strong and with or aspecting the planet that it is the sole enemy of, then the Dasha of that planet is detrimented.
The trick to remembering sole enemies is to count up six planets (inclusively) in the Dasha sequence, to find a planet's sole enemy.
In the diagram above, six up from the Moon is the Saturn, so the Moon is Saturn's sole enemy.
And six up from Jupiter is Venus, so Jupiter is Venus' sole enemy.
Because Rahu and Ketu are always opposite or conjunct in D-charts, Ketu has no sole enemy.
D. Multiple Malefics. If a Dasha lord in a sub-chart is aspected or with two or more malefic planets, they will detriment the theme of the D-chart for that Dasha lord.
E. Strong Yogas in the Birth Chart. If a Dasha lord participates is strong yogas in the birth chart, the Dasha may go well even if the Dasha lord is poorly placed in specific D-charts. E.g. If a person has strong yogas for finances (strong Dhana yogas) then the Dashas of the yoga-forming planets will go well even when the planets are poorly placed in the D-4, D-10 and D-11 charts (the divisional charts that speak to finances).
F. Weaknesses in the Birth Chart that affect D-charts. If a planet is within 3 degrees of the Sun (combust), the Moon is very Dark (within a sign of the Sun), or the planet is in a planetary war (within 1 degree of another true planet), then the planet has a weakness that will diminish the positive effects of a good placement in any D-chart and magnify the challenges of poor placements in any D-chart.
G. With a Debilitated Planet. If a Dasha lord is in the same house as, or aspected by, a debilitated planet in a D-chart, its Dasha will be somewhat disrupted and more troublesome for the themes of that D-chart.
H. Flanking. If in the house behind a Dasha lord (in a D-chart) and in the house ahead of the Dasha lord are only malefics, the Dasha period becomes somewhat more challenging. If only benefics flank the Dasha lord (in the houses before and after), the Dasha goes better than expected for the themes of that D-chart.
I. An Important Exception to the Papa Sankhya Yoga. If Saturn, Mars, or the Sun is in its own or exalted sign in an Angular House (1, 4, 7, or 10) and in the paired house is Mars, Saturn, or the Sun in its own sign or exalted, then the Dashas of both planets go well.
For Fixed Sign Ascendants, if the Sun is in Leo and Saturn is in Aquarius, in houses 1-7 or 4-10, this occurs. For Cardinal signs rising, if Mars is in Aries and Saturn is in Libra, in houses 1-7 or 4-10, this occurs. These are the only places where this special exception to the formation of Papa Sankhya Yogas can take place.
J. The D-11 chart. Only in the D-11 chart does the specific meaning of each house gain importance. (In the Iyer method, only the positive or negative nature of each house is important.) If, for example, one is running the Dasha of a planet placed in the 7th house in the D-11, it can mean either that the person gets married, or that the person gets honored through their spouse. In general, during the Dasha of a planet well-placed in the D-11, the person gets honored for the themes of that house.
K. The Importance of Planetary Strength and Weakness in D-charts. If a Dasha lord is in its own sign, Vargottama, has dig bala, is exalted, or is retrograde (or any combination of these) then that Dasha lord's strength will help them navigate the themes of that D-chart well, and deal with challenges better. If, on the other hand, the Dasha lord is debilitated in the D-chart, the person may find it harder to adjust to challenges that arise.
L. Yogas in D-Charts.
As mentioned in part H above, Kartari (Flanking) yogas do have relevance to D-chart analysis. So do others. E.g. A planet in an angle that's exalted or in its own sign, for example, forms a Pancha Maha Purusha yoga.
The rule of thumb in determining which yogas to apply in D-charts is to focus on yogas that involve house placement and are not based solely on house rulership.