 Suppose it is not the case that \(a\) be existent now in some other frame \(F'\). It seems as if this difference must result from \(a\)’s being simultaneous with some spacetime point \(\mathbf{O}\), say, in \(F\) while not being simultaneous with the same point \(\mathbf{O}\) in \(F'\). But on this reading Sellars’ schema is just a round-about way to indicate that simultaneity is relative—the point of departure for our metaphysical questions rather than the answer to any.