"Note" we did not go into how we made the force nor how we knew its quantity - must we?"

Well, for completeness of understanding... At some point, yes, we should. And that's partly my point.

How can we say we understand a thing if we can't re-articulate it?

Or how ca we say we understand a thing completely unless ew can articulate each piece individually?

I guess that's kind of my point with Mass. We know how it plays into equations and that the equations work. But we seem to be unable or barely able to actually articulate what "Mass" actually means or how it operates.

Of course that's my thought on the matter.

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"A note, though: If you are talking about the various speed of light and frame of reference issues, you are talking special relativity. If you are talking about gravity, then you are talking general relativity. When a layman (like me or you) mixes them together and tries to come up with contradictions, then he will likely give himself a headache, and come up with nothing useful."

Well, then that seems to be an issue. It's kind of bizarre to have two entirely different realms in which we have to talk... I guess it becomes a question then of why there isn't one unified continuum we can talk within without having to switch back and forth between general and special relativity... THAT is what gives me a headache.

IE, why can we talk about gravity in general relativity, but not in special relativity? And why can we talk about light in special relativity but not in general relativity? That just seems bizarre. Maybe you over-simplified and I didn't get the gist here. Or maybe I'm just confused in general (it's possible!).

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You're right, I was bit confused on the whole mass/acceleration/gravity thing, glad it came through. ;o] But it seems to be a confusing subject in general.

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"Purists will tell you it is a falacy to think of gravity as a force, like this, but it really does work if you do, so let's go with it. Yes, the bodies 'pull' each other. Yes, they resist that 'pull'. Else they would instantaneously head for each other at the speed of light."

Well, I guess I'm still confused on this point. How are they resisting the acceleration, if they're causing the acceleration?

Well, perhaps if we break it down, to a non-mutual attraction. IE
A pulls B. B resists A.
B pulls A. A resists B.

It may not be mathematical, but if we put the two masses together we could also say:
A exerts pull on B. B exerts pull on A. (Seems mutual.)
A resists the pull of B. B resists the pull of A. (Also seems mutual.)

So, how are they creating acceleration and resisting acceleration at the same time? One would think that these would cancel out and they'd remain at rest.

Of course, if they create more of a pull than they are able to resist, they'll accelerate, or at least one of them will.

I'd still wonder A) HOW do they create a pull. B) HOW do they resist each other's pull?

Again it comes back to the issue of "We think/know THAT they do it" but, "Do we understand HOW they do it?" Existence of feature versus causation. I'm interested in "understanding" causation, not just "utilizing" existence [in equations].

Hard question. But interesting to me...

Down and down we go, round and round we go ... In a spin, loving the spin we're in ... (Old Black Magic)

Or something like that.