This fatality (no photograph without something or someone) involves Photography in the vast disorder of objects—of all the objects in the world: why choose (why photograph) this object, this moment, rather than some other? Photography is unclassifiable because there is no reason to mark this or that of its occurrences; it aspires, perhaps, to become as crude, as certain, as noble as a sign, which would afford it access to the dignity of a language: but for there to be a sign there must be a mark; deprived of a principle of marking, photographs are signs which don’t take, which turn, as milk does. Whatever it grants to vision and whatever its manner, a photograph is always invisible; it is not it that we see.

In short, the referent adheres.

Roland Barthes on each photograph's relation to its referent. (#)