hi gaer,
i like your energy and philosophical position on the topics you are discussing here.
I don't want to write a book, so I'll try to answer some of your thoughts, on the fly. It's great to have an in depth discussion of such matters.
About age 30: the link to Saturn is obvious. What I hear less about is Uranus, which forms a square to itself at age 21. Then at age 28 (approximately) it trines itself. At 21 we have an incredibly strong need for independence and often find outselves totally at odds with our parents, or society in general. "Never trust anyone over 30." The middle 20s can be a period of incredible freedom, and by that time we may have jobs that allow us to do the things we want to do. We are old enough to be treated seriously. Our bodies are still young. At this age we see athletes hit their peak, although in some sports they may continue for another decade. But not in sports like tennis, where endurance and recovery time rule everything.
Somewhere between about age 28 and a year or so later, as age 30 is just around the corner, all sorts of things change. People who are unusually wise in their 20s sail through this difficult period, but I think even they usually have to make some kind of difficult adjustment. Those of us who have not been doing our homework get slammed by reality. I think that about age 30 we realize, for the first time, how mortal we are.
At age 30, approximately, I not only had Saturn conjuncting itself, it all happened in the 12th. At the same time I had Pluto transiting my 2nd house, all my Libra planets, including Sun and Moon. Uranus conjuncted Mars. I think what happened should be rather obvious to anyone who has studied charts and transits.
I think we are all potentially able to read our own charts better than anyone else, dependent on how hard we have worked to be honest with ourselves.
When Saturn entered the first quadrant when I was very young, I was cut off from other people. I lived in my own world and had no friends. Almost exactly as Saturn moved past my IC, and away from my 2nd house and 3rd houses, everything changed, though slowly. At the end of high school, just about the time Saturn moved past my DC into the 7th, I got nothing but recognition, and the moment I entered college my life totally changed. Looking back at the whole cycle, I can see clearly just how it all played out. I had my greatest success about the time Saturn passed my MC. I became invisible, again, when Saturn passed into my first quadrant again for the 3rd time (past the second Saturn return). Just now Saturn has moved past my 2nd house planets, presently Rx but not again getting any closer than 5 degrees to my Moon, and after three years of nearly losing my career it has come roaring back.
So in my life these cycles have been eerily valid.
The "pay the piper" theme in my life is directly linked to dealing with loneliness (Saturn/Venus in the 12th) combined with explosive, destructive anger (Mars/Pluto square, among other things). It is about learning that loneliness is not caused by being a victim, it is caused by what we project, and I was projecting arrogance, coldness, and to some extent cruelty (because of fighting back imappropriately), and it was all destroying my life.
When I think in terms of reincarnation, even considering it as a reality, I always see myself as a responsible, honorable person with power, but one who was incredibly intollerant, judgmental. Sort of a cold-hearted judge, condemning other people whom I did not see as worthy of being respected or deserving compassion/mercy. Everytime I go in that direction in this life, I get totally slammed. I see other people getting away with it, although I am sure that ultimately it will destroy them too. For me it feels as though I get no breaks in that direction, and it feels RIGHT that I don't get them. At some point we become aware of incredible faults, and ignorance is no longer a defense. We feel that they are deeply ingrained, habits, and suddenly they just don't work any more. We HAVE to change.
That is how I see 12th house lesson. Thus the potential undoing. You learn and change, or you are destroyed. No more free passes. Time to do hard work!
That's where the comment about "not being kind" came from. I was radiating coldness, arrogance. People who are very judgmental are cruel. When I began studying astrology and considering reincarnation, it was very easy to imagine what I said above. You can't be kind in this world if you are convinced that you are better, or superior to others. And that was where I was stuck. I still take on that attitude when I am angry or resentful, but now I catch myself about 1000 times faster and keep moving forward on a different path.