This interview with F. Varela was carried out at the end of January 1992 at the CREA of Ecole Polythecnique of Paris. The aim of the interview was to highlight the biological bases both of thought and of the epistemological analysis of Varela. In this sense the epistemological issues focused by Varela must be considered in the framework of the non separability of the living aspect from the cognitive one; therefore the approach to cognition must be an approach to life. In the interview some epistemological issues are dealt, starting from a synthetic reconstruction of some significant steps of Varela's thought, that were tackled from the viewpoint of the life/cognition relationship. This enabled Varela to define his position with respect to the radical constructivism. It is therefore necessary to define not only what is meant with cognition, but also wich is the main characteristic of life.