  To explain this proposition, Gueroult draws a distinction between “modes of substance” and “modes of attributes.” The claim is that 1P28 treats only modes of substance and not attributes, and is therefore unique. In other words, the identity is then understood in reference to “modes of substance” and not “modes of attributes” (Gueroult, 1968, 338–39). Again, we see an attribute-independent structure—the chain of modes of substance—that is meant to account for the “one and the sameness” of modes of different attributes.