Durkheim's 'Dualism of Human Nature' (1914) is the last scientific work by him published in his lifetime. This circumstance, and the subject of the essay, can suggest it is the definitive exposition of his philosophical view of human nature as homo duplex. But readers do not agree about the description of this view. What kind of dualism has he in mind, and is he consistent about it throughout his work? The problem is that his essay gives different meanings to the doubleness of human nature and combines them in a complex model of explanation. Reconstructing this model can throw new light on what is really at stake in Durkheim's text and on the nature of the dualism he upheld at the end of his career.