[General System Theory]... is a logico-mathematical field, the subject matter of which is the formulation and derivation of those principles which hold for systems in general.

Ludwig von Bertalanffy (September 19, 1901 – June 12, 1972) was an Austrian-born biologist, who grew up in Austria and subsequently worked in Vienna, London, Canada, and the USA. He is known as one of the founders of general systems theory; an interdisciplinary practice that describes systems with interacting components, applicable to biology, cybernetics and other fields. Bertalanffy proposed that the classical laws of thermodynamics applied to closed systems, but not necessarily to "open systems," such as living things. His mathematical model of an organism's growth over time, published in 1934, is still in use today.