2.1512 It is like a ruler laid against reality.
OK, so perhaps they are not one. But think of a map, to scale, laid right on top of reality. That is what a picture is like. And now recall that reality includes the non-existence of states of affairs and that pictures can represent the non-existence of states of affairs. So what is the relation between a non-existent state of affairs and a perfectly corresponding representation of it? Can we be sure that the relationship is not one of identity in fact (or in effect)?
Ostrow (p. 35) notes that a ruler does not use itself. We must apply it. He quotes Wittgenstein (Ludwig Wittgenstein and the Vienna Circle p. 185) saying to Waismann later that he might as well have called propositions measuring-rods as pictures.