  For many commentators, P2 states that forms are related to other forms, but not to sensible things, and P3 states that sensible things are related to other sensible things, but not to forms (see, e.g., Ryle (1939), Cherniss (1944, 282 ff.), Chen (1944), Runciman (1959), Schipper (1965, 15), Matthews (1972), Weingartner (1973, 185–187), Fujisawa (1974, 30 ff.), Shiner (1974, 24 and 31), McCabe (1994, 90–94), Gill (1996, 45–48), Sayre (1996, 88–91), and Allen (1997, 193–203)). But there are good reasons for thinking that this interpretation is incorrect (see Forrester (1974), Lewis (1979), Peterson (1981), Yi and Bae (1998), and Rickless (2007, 88)).  Plato’s formulation of P2 and P3 presupposes a distinction between two ways of being: relative being and absolute being.  Something has relative being if it is impossible to describe its nature without mentioning something else to which it is related.  Something has absolute being if it does not have relative being.  The point of P2 is that it is in relation to another form that any form with merely relative being is defined. The point of P3 is that it is in relation to another sensible thing that any sensible thing with merely relative being is defined. This reading is confirmed by Parmenides’ illustrations of P2 and P3. Mastery itself, he says, is what it is in relation to slavery itself, but it is not the case that mastery itself is what it is in relation to a human slave. Similarly, slavery itself is what it is in relation to mastery itself, but it is not the case that slavery itself is what it is in relation to a human master. Moreover, a human master is what he is in relation to a human slave, but it is not the case that a human master is what he is in relation to slavery itself.  Similarly, a human slave is what he is in relation to a human master, but it is not the case that a human slave is what he is in relation to mastery itself. Parmenides then instantiates P3 using the example of knowledge: