 A further condition of adequacy for an account of scientific representation is that it must account for the directionality of representation. As Goodman points out (1976: 5), representations are about their targets, but (at least in general) targets are not about their representations: a photograph represents the cracks in the wing of aeroplane, but the wing does not represent the photograph. So there is an essential directionality to representations, and an account of scientific, or epistemic, representation has to identify the root of this directionality. We call this the Requirement of Directionality.