  Socrates does not explain how this is supposed to be possible, but we can extract an explanation from what he says later in his speech about the properties of being one and being many, and from what the Phaedo tells us about the properties of being tall and short. At Parmenides 129c, Socrates claims that he himself is one (being one among the seven persons who are present) and many (in having many parts: right/left, front/back, upper/lower). At Phaedo 102b ff., Socrates points out that Simmias is taller than Socrates (and hence tall), but that Simmias is also shorter than Phaedo (and hence short). Thus, Simmias is both tall and short. Clearly Socrates envisages the possibility of sensible things being both like in one way and unlike in another. For example, Socrates is like Plato (in that each is a philosopher) and unlike Meletus (in that one, but not the other, is a poet). Being like Plato, Socrates is like. Being unlike Meletus, Socrates is unlike. Hence Socrates is both like and unlike. The general principle here is Impurity-S: