"Lives and Opinions of Eminent Philosophers" by Diogenes Laërtius contains a peculiar classification of contraries by Plato:
In physics one can also propose a similar classification of contrary physical quantities:
The contrary physical quantities of the first two kinds are contrary due to laws of physics. For instance, it is the law of energy conservation that makes force and displacement contrary. Similarly, these are laws of nature that entail that temperatures are averaged when masses are added up. But the contrary physical quantities of the third kind are contrary due to their definition and not because of some law of nature.
Surprisingly, nevertheless, for some of the contrary physical quantities of the third kind there are physical effects that relate them. For example, EMF across a circuit consisting of dissimilar conductors depends on the temperature at points of contact of the conductors. This is so called thermoelectric effect:
EMF at any point of a circuit = F(temperature at a few points in the circuit)
What if for any global physical characteristics that does not vary across space there is a physical effect that relates it to the values of a local physical characteristics at some spots ? That would be a powerful heuristic pointer to where to search for new physical phenomena.
Generally, it is worthwhile to search for how various global quantities/parameters/characteristics depend on local ones:
global characteristics = F(local characteristics)
It is also worthwhile to try and find new effects that relate physical quantities that do not vary over time (like energy or momentume) to those which do.
This is how reading ancient philosophers serendipitously led me to inventing new heuristic rules of searching for new physical phenomena.