Ludwig von Bertalanffy Quote
From the physical point of view the characteristic state of the living organism is that of an open system. A system is closed if no material enters or leaves it; it is open if there is import and export and, therefore, change of the components. Living systems are open systems, maintaining themselves in exchange of materials with environment, and in continuous building up and breaking down of their components.
Von Bertalanffy (1950) "The Theory of Open Systems in Physics and Biology" In: Science, January 13, 1950, Vol. 111. p. 23