Humans behave in orderly manner without rules
Human activity may be described by rules, but these rules are not necessarily followed in producing the activity.
Hubert Dreyfus, 1972.
For example, if I wave my hand in the air, touch something acidentally, and move my hand back to that spot, I am performing a complex series of movements which can be described geometrically, but the only principle I follow is "Do that again".
Similarly, the planets are not solving differential equations as they revolve around the sun, even if their movements can be described by differential equations.