We directly know only our perceptions. From these perceptions we
construct models of external reality. These models say more (at least as
much) about us and our modes of thinking than about the objective reality
under examination. We try to make sense ("our" sense) out of these
perceptions by externalizing substantial entities (objects, things,
substances) and by positing interactions among these objects. The
Newtonian physicist quantifies this model by inventing the quantitative
concept of "force". He categorizes and quantifies these forces by
defining into existence (inventing) quantifiable "properties" which he
associates with (his model of) an object in order to enable this human
description in a quantifiably useful and testable way.
In our direct perceptions, objects change their states (kinematical and
otherwise). We model these changes as interactions, which we further
divide into gravitational, electrical, etc and further describe in terms
of humanly invented properties (charge, mass, etc). Objective reality
(whatever it may be) knows nothing of this language or of these human
categorizations and abstractions.
I guess what I want to point out is simply the importantance of realizing
that this thread is not about external reality - it is about our models of
external reality - largely an introspective self analysis (a very useful
exercise).