Day-to-day reality appears to operate according to an underlying set of fixed rules. The reason I can say that is because physics has very successful at finding such rules, and writing them down as equations. Some of these equations are known to be astonishingly accurate.
The equations contain constants - like C, the speed of light, in Einstein's famous
E = M C ²There are a dozen-odd fundamental constants, total, with names like Planck's Constant and the fine structure constant. These are numbers, and they are fundamental if we don't know how to calculate their values. We have to learn the fundamental values by experiment.
Physics still has unsolved problems. So, physicists are looking for what some call the TOE - the Theory Of Everything. There was even a book a while back called Dreams of a Final Theory. Any new theory would be considered very impressive if it correctly predicted one of the constants. If the new theory became accepted, that constant would no longer be fundamental: it would be a derived constant.
If someone were to find a TOE which predicted all of the dimensionless fundamental constants, then that would be perfection.