 But Aristotle rejects this answer as impossible (1029a28), claiming that substance must be “separable” (chôriston) and “this something” (tode ti, sometimes translated “some this”), and implying that matter fails to meet this requirement. Precisely what the requirement amounts to is a matter of considerable scholarly debate, however. A plausible interpretation runs as follows. Separability has to do with being able to exist independently (x is separable from y if x is capable of existing independently of y), and being a this something means being a determinate individual. So a substance must be a determinate individual that is capable of existing on its own. (One might even hold, although this is controversial, that on Aristotle’s account not every “this something” is also “separable.” A particular color or shape might be considered a determinate individual that is not capable of existing on its own—it is always the color of shape of some substance or other.) But matter fails to be simultaneously both chôriston and tode ti. The matter of which a substance is composed may exist independently of that substance (think of the wood of which a desk is composed, which existed before the desk was made and may survive the disassembly of the desk), but it is not as such any definite individual—it is just a quantity of a certain kind of matter. Of course, the matter may be construed as constituting a definite individual substance (the wood just is, one might say, the particular desk it composes), but it is in that sense not separable from the form or shape that makes it that substance (the wood cannot be that particular desk unless it is a desk). So although matter is in a sense separable and in a sense a this something, it cannot be both separable and a this something. It thus does not qualify as the substance of the thing whose matter it is.