The gravitational force is the property of elementary particles but it cannot be directly observed, because it is extremely small: for an electron it is equal to 10E-39 of electrical forces.
I don't know what a progress physics made last years but according Einstein's relativity we were unable to distiguish gravity force from force due acceleration. So I think gravity is not good example considering the fact that grativity constant can probably change during time (according Dirac and some other nowadays scientists too).
A system acts as a “magnifying glass” and a “litmus paper” that reveals properties of the parts not observable otherwise. This means that a nature of complex things could be reduced* to the nature of sums of simpler or more fundamental things and therefore a WHOLE IS EQUAL TO THE SUM OF ITS PARTS.
This is interesting. It sounds like some ancient theories that in microcosmos is hidden macrocosmos.
Anyway in time being I am convinced that studying lower levels (reductionism) did not help in biology to underestand higher ones. Adolf Portmann dismissed such studies too - studying what is behind scene/stage doesn't help us to underestand what is Shakspeare play about either. Studying genome sequences do not explain mimicry patterns on wings - their meaning, their evolution etc. I have written about this in thread Mimicry and neodarwinism.