What is Madness? 4 Lacan's symbolic order

In this fourth post on Darian Leader's What is Madness? I continue my reading of his presentation of Lacan's ideas and their significance for understanding psychosis. My intention is to begin to get a handle on Lacan, distinguishing what makes sense to me and what isn't yet clear enough to grasp.

Leader begins his exposition of the symbolic order by describing it as a network of inter-related tacit rules (e.g. against incest) governing the family and society. This segues into a discussion of how language allegedly, and according to Levi-Strauss, introduces (p. 51) a 'certain negativity' into our experience of the world, 'building our worlds at the same time as creating a certain distance from them.' What this means isn't immediately clear, but the following ideas emerge from the text.

• First, that entry into the symbolic order involves a transformation of lived bodily experience. The infant who is at first polymorphously perverse experiences a 'draining and restructuring of bodily excitation.' We learn when not to shit, touch ourselves, eat, talk, undress, etc. This symbolic system of rules 'clips the body, removing libido.' 
• Second, that (what a Kleinian would call) the symbolic equations of a child, in which surroundings become fascinating because they are equated with bodily functions or parts (a hole in the wall evokes a vagina or mouth), need to be displaced by the symbolic order if terror is not to predominate. Without symbolisation, 'the world would just be one immense body and the hole in the wall might threaten to swallow up the child.' 'If too much of the body is present, we cannot enter a shared, social space.' 
• Third, that psychosis can involve a failure of the symbolic order in the same way that Segal suggests (concrete symbolic equations of bodily functions and worldly events dominating over the system of symbolism proper).

For the moment I think I must just acknowledge that these ideas sound interesting, but give me far too little by way of determinate content for me to be able to adequately conceive of what would confirm or disconfirm them in the clinic. Perhaps Leader is not so much offering an empirical theory, however, as a way of thinking. About that I must as yet remain silent.