What we call growth of even a simple organism is a tremendously complex phenomenon from the biochemical, physiological, cytological, and morphologica… - Ludwig von Bertalanffy

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.

Science in the past (and partly in the present), was dominated by one-sided empiricism. Only a collection of data and experiments were considered as being ‘scientific’ in biology (and psychology); forgetting that a mere accumulation of data, although steadily piling up, does not make a science.

Biological communities are systems of interacting components and thus display characteristic properties of systems, such as mutual interdependence, self-regulation, adaptation to disturbances, approach to states of equilibrium, etc.