"To live is to know"

Well, only if you take Matura's and Varela's definition into account, since they make a radical expansion on the concept of cognition. In this view, cognition involves the entire process of life - including perception, emotion and behavior. And not necessarily involve the brain and nervous system.
So yes, with this definition I do agree. I think "cognition", knowing, is much more than only some braincells firing. I think our high level brain (responsible for reasoning, decision making, social behavior and creativity) and low level brain regions (who regulate the processing of emotions and feelings, and have direct and mutual relationships with virtually every bodily organ), nervous system, sensory and motor peripheral nerves (that carry signals from every part of the body tot the brain, and from the brain to every part of the body) and the bloodstream (carrying chemical signals such as hormones, neurotransmitters, and modulators) all are cognition, because they all help us to know. And I think we interact with the environment as ensemble and the physiological operations that we call the mind are derived form the structural and functional ensemble rather than from the brain alone. So yes, mental phenomena can only be fully understood only in context of an organism’s interacting in an environment.