Three words. To actually perform said feat is something else entirely.

The words suggest the thing, but they are not it. This discrepancy between language and real stuff usefully delineates two types of understanding for any given posture or motion—one conceptual & the other embodied.

Take rectilineal standing:
A conceptual understanding would be to apprehend the concept of head over shoulders over pelvis over knees over feet.

An embodied understanding would be to do it—& crucially, to experience it.

One form of understanding is not better than the other. But if one were better, it would be the second. This is because it is more useful as a catalyst for lasting change. Often, the first sort precedes the second in sequence; experience then follows in the former's wake. Once a fellow has performed a given movement, he has also embodied it.In a way that mere intellectual understanding can never manage, embodiment allows for a return even when one's daily responsibilities loom forth & one is summoned off by Cretans to slay the Minotaur or other monsters. Duties demand our attendance. But like Perseus' trick, afterward, we can trace the thread left behind by our embodied experience, provided we have sufficiently cultivated the feeling of a given physical condition. If we have taken time to lay this thread, we trace it back out of life's labyrinth to the place of ease. We find with practice, our footsteps wear this path ever plainer & eventually we hardly need to trace it anymore—our feet know the way. With words, we speak about this path. But only by experience do our footsteps etch the trail in immortal stone. To utter "moonlight" is just noise—not the same as soft rays upon the maze's lithic walls. Literally, through practice, we develop the capacity to maintain ease in our bodies, even in adverse circumstances.

I could write about Rolfing® SI till the moon sets & the cows come home. And I would probably enjoy it. But

Conceptual comprehension really serves little purpose in this regard: the only way to discover what Rolfing SI is is to try it.