The biochemist Lawrence Henderson was influential through his early use of the term “system” to denote both living organisms and social systems. From that time on, a system has come to mean an integrated whole whose esential propierties arise from the relationships between its parts, and “systems thinking” the understanding of a phenomenon within the context of a larger whole.
This is, in fact, the root meaning of the word “system”, wich derives from the Greek 'synhistanai' (“to place together”). To understand things systematically literaly means to put them into a context, to establish the nature of their relarionships.
Fritjof Capra. The web of life.