  Another option (Rickless 2007, 54–55; see also Miller 1986, 46) is that Plato means us to recognize a tension between Self-Predication and Separation (or Non-Identity) in the theory of forms. On the one hand, the fact that justice is just, beauty beautiful, and goodness good does not suggest that justice, beauty, and goodness are concrete, sensible things. That is, Self-Predication gives us no reason to deny that justice, beauty, and goodness are separate forms, numerically distinct from sensible things. By contrast, if there are forms for human and mud, then Self-Predication requires that the human be a human being and the mud be muddy. It is difficult to see how human things and muddy things could be non-sensible. So Self-Predication gives us at least some reason to deny that there is a form for human and mud that is distinct from every sensible thing. This interpretation meshes well with Socrates’ remark that hair, mud, and dirt “are in fact just what we see” and that it is for this reason that “it’s too outlandish to think there is a form for them” (Parmenides 130d3–5).