"A cognitive system is a system whose organization defines a domain of interactions in which it can act with relevance to the maintenance of itself, and the process of cognition is the actual (inductive) acting of behaving in this domain. Living sytems are cognitive systems, and living as a process is a process of cognition. This statement is valid for all organisms, with and without a nervous system."
H.R. Maturana e F.J. Varela, "Autopoiesis and Cognition"