“In some regions, under especially favorable conditions, the level of organization reaches that of enormously heavy organic substances, such as protein molecules and nucleic acids. Now the basic building blocks are given for the constitution of self-replicating units of still higher organizational level: cells. These systems maintain a constant flow of substances through their structures, imposing on it a steady-state with specific parameters. The inputs and outputs may achieve coordination with analogous units in the surrounding medium, and we are on our way toward multicellular phenomena. The resulting structures — organisms — are likewise steady-state patterns imposed steady-state patterns imposed on a continuous flow… The organic systems themselves, define the supra-organic (ecological or social) community. Ultimately the strands of communication straddle the space-time region within which the primary systems have come together, and those of its layers which provide conditions favorable to such structuration become organized as systems in their own right. We reach the level of the global (ecological, and on earth also sociocultural) system.”

Source: Introduction to Systems Philosophy (1972), p. 83.