Using the example of psychosomatic diagnosis, I argue that the clinical context has unique epistemological constraints that limit the certainty of diagnosis and so make meaning indeterminate for sufferer and healer. As a result, forms of clinical truth are borrowed from the therapeutic context to create and authorize meanings for ambiguous or ill-defined conditions and inchoate suffering. Diagnostic interpretation is concerned with classification and legitimation through the production of authoritative truth. In contrast, therapeutic interpretation is fundamentally concerned with the pragmatic problem of "how to continue" and hence, with the improvisation of meaning. These different ends give rise to tensions and contradictions in psychosomatic theory and practice. While authority is necessary to provide a structure on which variations of meaning can be improvised, authoritative meanings may also restrict the possibilities for invention by clinician and patient. The goal of patient and physician is to create enough certainty to diminish the threat of the inchoate while preserving enough ambiguity to allow for fresh improvisation. Accounts of illness meaning must recognize the interdependence of normative rigidity and metaphoric invention.