Wittgenstein, in TLP 3.332, says something about sentences which sounds awkward, but is perfectly clear when applied to pictures. So the insight in the lemma may well depend on his picture theory of language. 3.332 No proposition can make a statement about itself, because a propositional sign cannot be contained in itself (that is the…

What is the isomorphy between a sentence and the world it describes? Looking at the photograph, and assuming the world was similar to what we see in it—let us say we hold the photograph up to the scene it depicts—it makes clear sense to claim that the fork is to the left of the plate…

…What is the logical formof a cup of tea half-filled with lemon juice?… A picture can depict only that which form it has. Sculptures depict the spatial aspect of things, paintings their colouring aspect. (2.171) What seems presupposed as a necessary condition is the sharing of the logical form between the picture and the depicted….