Pushing and Aspectual Mechanics
Planetary aspects are a tremendously important part of astrology. Through these contacts planets either assist or harm their fellows or will otherwise augment their character or the manifestation of what they are signifying. Difficult aspects typically harm or destabilize, while friendly aspects will assist and secure.
Aside from bonifying with trine aspects or afflicting with square aspects, the process of application has another function. The medieval tradition would refer to this as "pushing"1 and there were a few different types with varying degrees of utility and frequency.
Pushing Power: This occurs when a planet in one of its dignities applies to another planet. Example: Moon in Cancer applying to Jupiter in any sign.
Pushing Management: Sometimes called "pushing council", this occurs during every applying aspect.
Pushing Nature: Occurs when a planet applies to another planet while being in that planet's sign. Example: Moon in Sagittarius applying to Jupiter.
As stated above, pushing management occurs during every applying aspect. Pushing nature and power occur in addition to management, but only happen under specific circumstances.
Pushing Management
Being the most common form of pushing, understanding the conceptual basis behind pushing management will set the foundation for understanding the additional actions pushing power and nature bring.
In this form of pushing, a faster planet hands over its significations to the planet it is applying to. It then becomes this heavier planet's responsibility to complete (or not to complete) the faster planet's business.
Since pushing management occurs during every single application, it is immensely useful in horary astrology where the immediate applications of significant planets will be the key clues to ascertaining the outcome of the question. However, merely knowing that pushing is occurring is not very helpful in itself. We need to examine the planet to whom management is being pushed to.
"Finally, in every affair the receiver of counsel should principally be noted, and what place from the east it maintains or holds on to. In fact, being free from the infortunes, nor scortched2, nor cadent, it takes care of the things asked about."
-Masha'allah
It is this rule that makes the Moon's next contact in horary, elections, and magic so important. The Moon is, essentially, passing off the intent of the question or event to another planet who will decide what to do with it. The quality of the receiver's actions can be ascertained through a list of criteria: 1) aspects involved 2) nature of the planet 3) strength of the planet 4) reception.
Applications through sextiles and trines are more likely to render good results than squares and oppositions. Similarly, the benefic planets Jupiter, Venus and the Sun are more likely to bring things to a positive conclusion than the malefic or neutral planets Mercury, Mars, and Saturn. Reception is also a major factor, as the malefic planets will perfect things if they receive the applications from some place they have essential dignity.
However, even if the application is being favorably received by a fortunate planet, it still may not be enough if the heavier planet is not in a good enough state to accomplish anything. Masha'allah gives us such an example in his text, On Reception.3
The above chart is for a question regarding obtaining a position within a kingdom. Here Masha'allah says that the Moon in Libra is applying an opposition to Saturn in Aries in the tenth house. Since Saturn is in the tenth (which is the quesited house), Saturn can perfect the matter for the Moon and bring the querent the position they desire. Luckily for the querent, Saturn receives the Moon into his exaltation of Libra and so chooses to perform, the querent gets their position.
Saturn, though is in his fall in Aries. This should be a source of concern as debilitated planets are not able to perform optimally. About this, Masha'allah says "...the smallness of its [the office] usefulness came about because of the fact that Saturn, who decreed a kingdom to him, by the command of God, was in the sign of his own descension, and of his evil, and worthlessness, and his well, and in a place in which he had no dignity. Even what of [the position] was given to him was hateful, on account of the hatred which Saturn had toward his own place."
We can see that, while the reception with Saturn allowed the querent to have the position of authority he wanted, he grew to dislike it and found it less advantageous than he expected.
Returning
The metaphor of planets pushing or handing over signification is pervasive in parts of texts that describe aspectual mechanics and there are also references to planets pushing back against the applying planet. This is the idea of returning. A planet being applied to hands the signification or power back to the applying planet, being unable or unwilling to do anything with what it is being handed.
Returning occurs when the planet being applied to is either retrograde or combust. Some sources refer to cadent planets as returning aspects as well, but this doesn't seem as common and doesn't fit as well as the other two conditions. When planets are in retrograde motion they are moving backwards through the zodiac. This means they effectively meet any planets applying to them in the middle, forming something often referred to as a "mutual application" (both planets are applying to one another). So the faster planet hands over its significations to the slower planet, but because the slower planet is also technically applying to the first planet, the slower planet just sort of hands back whatever the first planet was trying to give it.
Something similar occurs with combust planets. Because they are combust, they lack their own light and are overcome by the intensity of the Sun. This renders them unable to really accept any pushing that comes from other sources. This is typically considered a form of returning, but may also be a case wherein the heavier planet simply cannot manifest whatever it is being tasked with.
This action of returning puts pressure on the applying planet. Suddenly realizing it has more responsibility than it initially thought, this faster planet must now manifest the thing as best as it can in its own condition. If this planet is itself well placed this should be fine, but it can be troublesome if the planet is in a difficult position.
Pushing Power
Even though pushing management suggests that lighter planets hand off their significations entirely, there are still circumstances when they have a direct effect on them even after handing them over to a heavier planet. These circumstances are pushing nature and power.
Pushing power has the most direct effect on whether something will manifest or not, while pushing nature is more effective over the quality, type, or condition of the outcome.
In pushing power, a planet in some of its own dignity applies to another planet and hands over management like in all applications. However, since the applying planet is dignified, it hands over some of the power or resources it has to its partner so that they may benefit from its strength. In the earlier example of the Moon in Cancer applying to Jupiter, it doesn't matter if Jupiter is ill dignified or afflicted, the Moon's strength can help give him a boost to do what he needs to do. Of course, this will have to be weighed against the other factors involved.
Pushing nature is the most mysterious of the pushing mechanics. There is not a lot of literature available about it, and there appears to be even less reference to it in classical chart examples. Part of the reason may be that the criteria for pushing nature (a planet applying to the domicile, exaltation, triplicity, term, or face lord of its degree) is the same as reception. It is likely that pushing nature eventually became engulfed by this more widely used technique.
What we do know about pushing nature comes from early Arabic sources like Abu Ma'shar and al-Qabisi. It is even mentioned in Abraham ibn Ezra's work. The technique suggests that when a planet receives the application of another from a place it holds dignity it accepts something of that planet's nature and expresses it itself. So while the lighter planet has passed off significations, it's also passed along some of its personality. This means that whatever results from the application will be of a nature similar to both planets. If the Moon were in Sagittarius applying to Jupiter, we would expect that whatever came out of it would come about in a combination of a Jovian/Lunar way instead of only a Jovian way.4
Conclusion
Aspects are typically only considered in regards to their form, but hardly ever their function. When discussing aspects the conversation is about if they are trines or squares, but never about what exactly is being transmitted. Awareness of the mechanics occurring behind the scenes of these contacts can help us better understand how they will ultimately perform and will allow us to more easily conceptualize other techniques like reception