Consider a pure, one isotope element. On a balance scale, imagine that we can place one atom at a time in a pan. We have a standard calibrated mass in the other pan. We can (theoretically) place one atom at a time in one pan until it is balanced against the standard mass in the other pan. When we lift either the pan with atoms or the pan with the standard mass we feel weight. We feel the combination represented quantitatively as the product [mg] at location [g]. The quantity [g] represents an acceleration that is dependent solely on a distance from a center.
In this thought experiment, we observe that the balance scale compares the resistance of a quantity of atoms to the resistance of a quantity of matter calibrated in mass units. Given that the thought experiment is valid, we feel (work against) at location [g], the cumulative resistance (mass) of the number of atoms in the pure object pan at that location.
The action of the balance scale, on balance, speaks only to the uniform attractive force on the contents of each pan. The balance scale does not tell us what kind of force is acting on the pans. We can look at it as though it is a uniform attraction on mass, (as Newton did) or a uniform attraction on atoms (where Newton did not require any greater distinction than mass). In either view, mass units are conserved. Question: What is it about mass that allows this?
I asked how we derived the quantity mass in the first place. Mass is the scalar component of force, where F=mg and F=ma. In the case of [mg] it comes from the balance scale. Each atom in the pure object pan is uniformly acted upon by the planet attractor. If this is correct we should be able to deduce the number of atoms in the pan by dividing the total weight by the weight of one atom, since in this gedanken all atoms are identical by definition. However, since the total weight includes [g], an outside influence, and the weight of one atom includes [g], also an outside influence, which outside influence acts uniformly on the balance scale as well, and on us as we observe the action, we can eliminate the quantity [g] from the frame of the balance scale action (adding it back in at any specific location to describe the force we must apply).
Since [g] is the same magnitude depending on location before and after we obtain a balance, the equation on balance where [mg]1=[mg]2 can be divided by [g] to yield [m]1=[m]2 on balance. This shows that the balance scale compares mass [m] (resistance) since the quantity [g] is a variable influence dependent on any location such a measurement can be made, the quantity [mg] represents a variable resistance, a magnitude of matter that we feel as weight, at any location we can use the balance scale.
Here it appears that we have defined gravitational force in terms that are subject to what we feel at any location in space. In this case we define the universe in terms of the force we feel and apply to a resistance and we generalize that force to the entire universe because we feel it everywhere. Since the resistance we encounter at any location [g] is equal and opposite to the force we apply at any location [g], the subject is closed. That's all we require to successfully operate within the least action universe.
What we feel is the product of resistance [m] at an accelerative location in space [g]. Where the balance scale solely compares the resistance [m], independent of any location [g]. But we always knew that, didn't we?
If you wish to review some of the foundational logic for the ideas expressed herein, do a Google.group search on: "The Least Action Consistent Stable Universe and the Mathematics, Sections 1 through 9", or "Randaminor", "Randamajor", "Thejohnreed", "Earth Attractor" or "Planet Attractor". To exhaust the search on the internet take your search back to 1998. To exhaust the copyright information take it to 1988 and "Pi and Angular Momentum in Perspective", "The Anti-Billiard Ball Hypothesis", and "The Physics Preview for the 21st Century".
I have made it easier to reference my supporting work by creating a Google Science and Technology Group titled: "The Least Action Consistent Universe and the Mathematics". Currently it contains Sections 1 through 9 as noted above. The many sub-sections and work prior to 2007 has not been included. I will develop it further as I gain familiarity with the venue.
Meanwhile it is available for public review to all, and open to criticism and discussion by any person who joins the group. No restrictions or requirements to join.
Endnote:  Section 5 and 6 as listed above provide a more comprehensive explanation of least action. For my purpose here the reader may substitute the word "efficient" for the phrase "least action consistent".