Laing writes that ontological security is related to feeling embodied. The embodied person has a sense of being flesh and blood and bones, of being biologically alive and real: he knows himself to be substantial... The individual thus has as his starting-point an experience of the body as a base from which he can be a person with other human beings.
This is in contrast to the insecure, unembodied person who is cleft into himself as 'mind' and himself as body. Such people do not seem to have a sense of that basic unity which can abide through the most intense conflicts with oneself and therefore are not secure in their own being. He describes these people as, if not always obviously and outwardly schizophrenic or otherwise mentally ill, at least having a vague and undeveloped notion of themselves as themselves and as being fearful of losing themselves; for example a woman who seems to 'become' her mother, or a woman who feels afraid when she is alone, as if she cannot constitute herself without others viewing her.
Feeling rooted in the body, according to Laing, is important because we experience everything via our bodies. If we split our mind from the body, and institute some sort of false self who is mediating between body and real self, then our experience of the world itself is mediated. We feel things as somehow being unreal/dead and our actions as being futile because our 'self' is not in direct contact with things.
Throughout this I was thinking that there is one obvious group who might feel unembodied and which Laing might want to differentiate from the 'insane' unembodied. He then goes on to give an case study of David, an 18-year-old who wears strange clothes and deliberately modifies his personality as if he is playing a part. But he also describes how David 'took over' from his mother, enjoys embroidery, tapestry and interior decoration, and could only feel spontaneous and absorbed when in front of a mirror playing the part of a woman - his mother, or female characters from plays. He found he could not stop playing the part of a woman. He caught himself compulsively walking like a woman, talking like a woman, even seeing and thinking as a woman might see and think. David is described as in fear of being entirely engulfed by the woman who was inside him, and always seemed to be coming out of him.
I think a modern reader may have a different diagnosis for David than the one of schizoid organisation that Laing assigns him. Of course, it is also true that David has a false self and is separated from his body, and that he wants to protect what he sees as vulnerable self, but one might see these as symptoms rather than condition. The Divided Self was written in 1960. The first widely publicised sexual reassignment, Christine Jorgensen, was in 1952. So it's not implausible that Laing might make some connection here. David is described as dreading and hating his female aspects rather than encouraging them, so that it seems Laing is saying these are the feelings of the 'true self' who is in danger from a female 'false self' and 'impersonation' who is just as unreal as the strange personality he puts on for others - but no attempt is made to determine whether precisely that is the protective mechanism and whether the roles have in fact been swapped.
Transgender people do in fact report feelings of self-hatred, depression, unreality, dissociation, bodily insensitivity, asexuality, lack of emotions, futility, roleplaying, etc - and the corresponding 'embodiment', discovery of emotions, genuineness, etc when presenting as the other gender.
While Laing encourages listening to patients and recognising that they are telling their own truth, he nevertheless sums up madness as being tested by the degree of conjunction or disjunction between two persons where the one is sane by common consent. The critical test of whether or not a patient is psychotic is a lack of congruity, an incongruity, a clash, between him and me. As example, he says I have no difficulty in regarding another person as psychotic, if for instance he says he is Napoleon, whereas I say he is not.
I wonder whether saying you are a woman would be regarded as psychosis if Laing says you are not.