# Information theory, introducing the concept of information as a quantity measurable by an expression isomorphic to negative entropy in physics, and… - Ludwig von Bertalanffy

Teleologie ist … ein Ausfluss der Systemgesetzlichkeit und damit ein legitimer Gegenstand naturwissenschaftlicher Forschung

We find systems which by their very nature and definition are not closed systems. Every living organism is essentially an open system. It maintains itself in a continuous inflow and outflow, a building up and breaking down of components, never being, so long as it is alive, in a state of chemical and thermodynamic equilibrium but maintained in a so-called steady state which is distinct from the latter.

A general proof is difficult because of the lack of general criteria for the existence of steady states, but it can be given for special cases.