Equilibrium v. Disequilibrium

I heard somewhere of a theory of children going through ebbs and flows of equilibrium (settled, easy going, pleasant) v. disequilibrium (where they are more unsettled, push boundaries, more difficult). Usually, these ebbs and flows correspond with a child's whole-birthday and their half-birthday.

I've thought a lot of this theory lately. Owen has been just so....pleasant lately. Maybe I shouldn't be surprised, but I feel like we just fought so many battles together this last fall between potty training, going to bed, listening, etc. And so, it surprised me a few weeks ago when after I put him to bed without a fight for a few days in a row, I reflected back on how it was not only going easier in going to bed, but really, in all aspects. He is more compliant, seeks to please, responds to discipline, etc...and he just turned three and a half!

We haven't done anything else different, really, in our parenting--so it made me start thinking of this equilibrium v. disequilibrium theory again.

Has anyone else felt/seen this in their children?

Big brother

After baths, I needed to do a few quick things. Owen crawled up on the couch and said,

"Mom, I can read Connor some books...it's what big brothers do."

And sure enough, he sat there and read a few books to Connor. It was so sweet.

He loved it.
Connor loved it.
I loved it.

A trinity of perfection!