Starting with the Natal and Transits chart, by looking at the planets’ position and the aspects they make to the natal planets, you can understand what is happening in your life. You have to look at the aspect that the transiting planets make to the natal planets but also the aspect that the natal planet makes to the transiting planet. And you also have to look at the aspect that the transiting planets make to the other transiting planets (the “celestial state” of the planets). The aspect formed by the personal planets will show what you are likely to do based on your own personal tendencies derived from who you are, from your own personality. The aspect formed by the transpersonal planets will give indications of what is likely to happen with regards to you and your life.

Here are some examples to illustrate.

Then you look at the Solar Arc and Transits chart to see if what the Natal and Transits chart is showing is related to an event, if it has to do with the outside world, or if it is purely yourself, your own actions and  your own personal life evolution that we are talking about here.

This is a subtle but key difference which is fundamental to the reading and understanding of the charts from a predictive perspective with respect to you and your life. 

Your actions, what you do, what is happening in your life based on who you are and your tendencies will be shown in the transits to natal chart.

These actions can be the result of your decision, your own will but they can also be triggered by the outside world interacting with your life, by external circumstance.
For example, you can decide that today you will apply to a job. The transit to natal chart will then show an aspect between transiting Mercury, the communication planet, or between transiting Mars, the action planet, and your natal MC, which represent your profession, your career, or the lord of your House 6 which is related to your work, job.
This is your own decision, your free will.
If you do not get to interact with somebody out there in relation to your application, if your application does not trigger any event in the outside world such as a recruiter or a human resource person reaching out to you following your application then only your transits to natal chart will show a relevant aspect between a transiting planet and a natal planet and there won’t be a corresponding/similar aspect between a transiting planet and a solar arc planet in the transits to solar arc chart..

But, as said, what you do can also be the result of external circumstances, the outside world interacting with your life.
So, for example, a recruiter  reaches out to you today regarding a job opportunity which will then triggered some action from yourself.
In this case, the transits to solar arc chart will show an aspect between a transiting planet and a solar arc planet which will be consistent with the event. Here it will be similar to the aspect(s) described here above such as transiting Mercury aspecting your solar arc MC or the solar arc planet which is the lord of your natal house 6. That is the recruiter reaching out to you in relation to your profession (MC), to a job opportunity (House 6).
And your transit to natal chart will show the same aspect as described before such as transiting Mercury or Mars for example making an aspect to your natal MC or to the natal lord of your natal House 6 which will show that you are doing something, that something is happening in your life at the personal level in relation to your profession or your work/job; that is that you are dealing with the recruiter.

This is how you can have both at the same time, indications of life evolution or personal action and indications of an event. But you can also have one and not the other.

If you do something that does not trigger any event in the outside world, it will be shown in the transit to natal chart by an aspect between a transiting planet and a natal planet but you won’t have a corresponding/similar aspect in the transit to solar arc chart between a transiting planet and a solar arc planet as nothing happens in the outside world.

If external circumstances, what happens in the outside world, trigger an event in relation to your life but you do not react to it, you do not do anything in relation to it (your free will), the transit to solar arc chart will show an aspect between a transiting planet and a solar arc planet but you won’t have a corresponding aspect between a transiting planet and a natal planet in the transit to natal chart as you do not do anything in relation to the event (your free will).

If you do react (your free will) to the event created by external circumstances, then a corresponding/similar aspect between a transiting planet and a natal planet and an aspect between a transiting planet and a solar arc planet will be seen in the transit to natal chart and  the transit to solar arc chart respectively.

The Natal and Solar Arc chart is very important and very useful to look at as it indicates the interaction of the outside world with your life, positively or negatively. It describes, it shows external circumstances interacting with and impacting your life.

The best examples to illustrate what it means is for example if Solar arc Saturn is making a difficult aspect to your natal MC or your solar arc MC is making a difficult aspect to your natal MC, then the circumstances in the outside world out there are such that they create difficulties in your professional life. The difficulties in your professional life are not the result of your own actions here or of somebody else by simply the result of external circumstances. and vice versa, if you replace Saturn with Jupiter in my example, then external circumstances, the world out there, are bringing a good time professionally to you.

For example, to illustrate what these external circumstances could be, think of somebody who works in the leisure industry and has lost his or her job in 2020 due to the Covid health crisis because the restaurants, hotels, bars, etc were all closed down. Or somebody who works in a bank and looses his or her job in 2009 because of the 2008 financial crisis. These are examples of external circumstances impacting negatively your life, of the outside world interacting negatively with your life. This is not the result of something that you have done or that you are doing. And it will be shown by a solar arc Saturn conjunct your natal MC or your solar arc MC square your natal Saturn. You are having a hard time re your profession. If you lose your job as opposed to other scenarios where it is a difficult time but without a job loss, that job loss event will be shown by a transit of a planet to a solar arc planet, for example of transiting Saturn to the solar arc planet that has lordship over your natal house 6. The transits to natal chart will show what your are doing, not the event itself. For example it will show an aspect between transiting Mercury (personal planet) and your natal MC which is showing that that day your boss is telling you that you are fired (communication/interaction in relation to your profession).

The solar arc to natal chart shows the outside world, external circumstances in relation to you and your life.

The transits to solar arc chart will show the event, the impact of these external circumstances to your life from an event, from the reality of life out there perspective. It is also the one to look at if you are looking at the timing of a particular event (job loss, marriage, contract signature, etc). 

The transit to natal chart will show what you are doing, your life evolution. You and your life.

Then you look at the Progressed and Transits chart to see what you feel in relation to your life and the outside world and events. That would then give another confirming indication with regards to what the Natal and Transits and the Solar Arc and Transits chart are indicating. If something happens in your life, you will “feel” it. But careful, the progressed chart is showing what you feel. It is subjectif and can sometimes be misleading.

The progressed chart shows your own personal evolution as a person, as a being, as a soul. That evolution can be the result of a precise event, being directly related to it (or a serie of events). But it can also not be related to any specific event in particular but being your own personal evolution resulting from what you have experienced so far in your life, recently or not, one specific thing or a all lot of different things, events, experiences that combined together over time and at this point in time (point in time not being just one day but a period in your life of a few days or weeks or even months as personal evolutions are slow) bring a personal change to who you are as a person, a being, a soul.

The Natal and Progressed chart as well as the Progressed to Progressed chart will show who are and who you have become as a person and what you feel. These are long cycles.

Finally the Solar Revolution chart will give additional indications of what to expect for the period from about nine months before to nine months after your annual birthday date and is useful in complementing and confirming what you’ve seen in the other charts and the interpretations you made using them for that specific period.