Sentience and Cognition

The outcome of the continued interactions of a structurally plastic system in a medium with redundant or recurrent structure . . . may be the continued selection in the system of a structure that determines in it a domain of states and a domain of perturbations that allow it to operate recurrently in its medium without disintegration. I call this process "structural coupling." If the medium is also a structurally plastic system, then the two plastic systems may become reciprocally structurally coupled. . . . . In such a case, the structurally plastic changes of state of one system become perturbations for the other, and vice versa, in a manner that establishes an interlocked, mutually selecting, mutually triggering domain of state trajectories.
		p. 35-66
Humberto R. Maturana	"Biology and Language: The Epistemology of Reality" Psychology and Biology of Language and Thought Academic Press, 1978
Essays in honor of Eric Lenneberg, edited by George A. Miller and Elizabeth Lenneberg.