Contributed by Antonio Grub
By determining the dominant triadic structure in a chart, one can learn much about the person to whom it belongs, including what their professional life will be like. The first order of business is to determine which, if any, rulers occupy the angles (the angles being houses 1, 4, 7, and 10). Some have planets on all four angles, others have planets on none. But if we assume there are rulers on one or more of the angles, we now need to determine which of them is of most practical use (in particular if any is a lord of action, which are Mars, Mercury, and Venus). If Mars is on one angle and Venus on another, or if Saturn is on one angle and Mercury on another, it is unclear as yet which planet would be most relevant to their professional career. It may well be the case that Saturn is the planet most relevant, but that will depend on whether any ruler occupying an anglular house is in fact part of a triadic structure.
By triadic structure, we mean a ruler on an angle which makes a hard aspect or a trine (that is, by sign only) to another ruler.
Suppose Mercury in the 7th house makes a trine to Saturn in the 3rd. We would need to see if another ruler also makes a square or opposition (by sign) either to Mercury or Saturn. If indeed Mercury makes a square to Jupiter in the 10th, then we have a genuine triadic structure of which Mercury in the 7th house is the hinge, or what might be termed the standpoint.
Let us invert the situation somewhat. Mercury in the 7th is opposite Saturn in the 1st, and Jupiter occupies the 9th. This would be a triadic structure wherein Saturn serves as the hinge and standpoint.
Another example would be if Mercury in the 7th makes a trine to Jupiter in the 3rd, and Saturn is square Jupiter in the 12th. Jupiter would become the hinge and standpoint because it is the source of both hard aspect and the trine.
Every triadic structure has a “home angle.” In Example 1, there is a contest between 7th and 10th. When we consider that the 7th is the hinge, we know it is truly the home angle, and that the 10th is not. Mercury and Jupiter vied for dominance, but since Mercury in the 7th served as the hinge, the 7th became the dominant or the home angle. Mercury is the only lord of action in this equation and it is unquestionably going to be a force in the native’s career.
In Example 2, the home angle is in fact the 1st house because it contains the hinge. In other words, the structure exists for the 1st house. But Saturn is not a lord of action, so we must default to Mercury again in the 7th as the site of activity which will then redound to the hinge.
In Example 3, Jupiter in 3rd is the hinge, and since there aren’t two angular positions competing we automatically know that the 7th house is the home angle. Jupiter is not a lord of action, so Mercury in the 7th’s professional practical actions will redound back to it. It is not to say that Jupiter cannot perform actions, only that its actions are less practical and will be aided by a lord of action.
Again, some have multiple triadic structures in their chart, others have none. For those that have multiple, the triadic structure, and its standpoint, most effective depends on many factors, including which triadic structure contains the most lords of action, or perhaps which features the 1st-house ruler, or 10th-house ruler. Those who have no triadic structure in their chart are interesting people, and can still achieve success, but along eccentric lines. It is also worth considering the outer planets which I have found do work within triadic structures. But I realize this is controversial.