Thomas Szasz
"[When] we speak of physical disturbances, we mean either signs (for example, a fever) or symptoms (for example, pain). We speak of mental symptoms, on the other hand, when we refer to a patient's communications about himself, others, and the world about him... the statement that "X is a mental symptom' involves rendering a judgment. (Szasz, 1982).
"[When] patients with demonstrable diseases of the brain are involuntarily hospitalized, the primary purpose is to exercise social control over their behaviour." (Szasz, 1974)