Causal States have a number of fascinating properties which make them ideal for representing natural processes
CS are Maximally Prescient, i.e. knowing the causal state a system is in is as good for predicting the entire future of the system as is knowing the entire past of the system.
CS have Minimal Complexity,
CS are Maximally Deterministic, i.e. given the causal states and another (rival) set of states which is equally prescient (good at predicting the future), the uncertainty of the next symbol is minimal given the causal states.