The important point that Becher introduced is that the explanation
of a natural phenomenon (i.e., model, theory) must be "testable"
In other words once a model is proposed as an explanation
of a phenomenon, it can only be considered a scientific model
if it can be objectively tested by experimentation.
Becher's proposed explanation of fire served this purpose
because the mass of the substance before and after combustion
could be measured.
Astrology, or the explanation of future events by the alignment
of astrological objects is an example of a non-scientific model
since an objective experiment to test it cannot be devised.