Psychoanalysis can be considered from three different viewpoints: first as a science and a theory of psychic functioning, secondly as an ethical system, and thirdly as a clinical practice. In this paper, we argue that these three perspectives are deeply inter-related, since they have everything to do with a fundamental structural underlying lack. We discuss why and how psychoanalytic ethics need to assume this lack, how the original contribution psychoanalysis can make to science is related to the study of it, and how psychoanalytic practice is faced with the continuous challenge of starting from the lack as a source of creativity.