Johnston C (2017) The Picture Theory. In: Glock H & Hyman J (eds.) A Companion to Wittgenstein. London: Wiley-Blackwell, pp. 141-158. http://eu.wiley.com/WileyCDA/WileyTitle/productCd-1118641167.html
First paragraph: What is Wittgenstein’s picture theory a theory of? An easy answer to this question is that it is a theory of representation, but insofar as this answer is indeed easy, so too is it uninformative. If I roll my eyes thereby communicating to an intended audience that the person I’m telephoning is being unreasonable, this will not be an instance of the kind of representing Wittgenstein wants to understand. So what does he want to understand?