Every model is an abstraction. This means that some information is
removed and/or lost in creating the representation. We attempt to
abstract away only the pieces that don't affect the results we seek,
and in doing so we assume that the system is made up of discrete,
isolated components that can be added and subtracted with little or no
impact on the rest of the system. (...)
Unfortunately, we tend to forget the approximation and assume that our
model is the real thing. Therein lies the danger: not approximation,
but ignorance.