This paper aims to clarify three issues: (1) the uniqueness of living and scientific knowledge, (2) the significance of communication in these two kinds of knowledge, (3) the potentiality of a double helix structure for the two kinds knowledge in chance discovery, i.e. collaboration between lay subjects and specialists. These tasks were approached through theoretical and empirical research using concrete data obtained from a questionnaire and a case study. As a result, specialists and lay subjects were found to have outstanding knowledge in mutually different contexts even though they had limitations; solutions to problems were obtained through collaboration using mutual knowledge that was obtained on an equal footing.