With a discussion of the key concept of Form behind us we may feel better equipped for our main task, an explication of the concepts of mind and matter. For reasons that will become apparent it is feasible to take the latter first. What is the analysis of body-related concepts? What in general are the criteria for counting as a sōmatoeides?1 To what category do they belong? Or less anachronistically: Would Plato regard, say, a stone, a book or a human body as a substance (ousia)? Or would he find a less honorific label such as genesis? What exactly is the import of the crucial term genesis?