"[1] And later in the book, "I use substitution in order to 'make believe' in its literal sense-- to make me believe [...], in order to send me into the moment-to-moment spontaneous action of my newly selected self on stage.
"[2] Hagen is clear that substitution is a means to further connect actors to their characters and the actions of the play, as opposed to, for instance, bringing on tears.
"[3] Hagen also warns against confronting any traumatic experiences, believing it to be unhelpful.
"There are teachers who actually force actors into dealing with something buried (their response to a death of a parent, or the trauma of a bad accident).
If you feel mentally sick or disturbed and in need of it, by all means go to a trained doctor or therapist, but not to an acting teacher.