(Recovered from my original notes)
I just had some thoughts that explain the origin of temperaments, most particularly introversion/extroversion.
Let us suppose that people are primarily Static or Dynamic, and Rational or Irrational. Extroversion or Introversion being a consequence.
Static people perceive reality as "fixed", "unchanging". Dynamic people see it as changing all the time.
Suppose that you are Static and Rational:
- "things aren't changing, and that is a sort of reassurance, this pleases me" -----> you become calm, unflappable, stable, and you see no reason to take action -----> you become introverted, an IJ.
Supppose that you Static and Irrational:
"things aren't changing, and that is a sort of boredom, annoyance, I gotta get some excitement" -----> you become impulsive, mobile, an extrovert, an EP.
BUT!!! Of course even an EP may decide that stability is a good thing in some aspects. In those aspects he will behave like an IJ - calm, unflappable. And even an IJ may decide that some stable things are boring. In those he will act like an EP.
Now suppose you are Dynamic and Irrational:
"things are changing, and this is good, it relieves me of boredom" ------> you become relaxed, go-with-the-flow, content, and see no reason to take initiative. You become introverted, an IP.
And if you are Dynamic and Rational:
"things are changing, and this is a source of nervousness, I wish they wouldn't change, I gotta do something to prevent the change, or to stay ahead of them" --------> you become restless, proactive, an extrovert, an EJ.
BUT!!!!! Of course even an IP will dislike some of the changes happening, and then he is also ennerved by them and springs to action. And of course even an EJ will welcome some of the changes, or not care about them.
That is why an IP can act as EJ, and an EJ as IP -- -- - and the same for IJ and EP.
And this is more likely than for an IP to act as EP, nor the EJ as IJ, etc.