Fifty helium-filled balloons are lifting a copy of the DSM-IV (Diagnostic and Statistical Manual of Mental Disorders) used by psychiatrists. The book comprehensively describes the characteristics of a mystical experience: hearing voices, seeing visions, experiencing a sense of disassociation, a loss of sense of time and space, and an inability to articulate the experience. All of these characteristics are however described in psychopathological terms and raise the question of the place of mysticism and acute religious experience in the field of psychiatry. Even after considerable changes to both the DSM-V and the 10th edition of the Classification of Mental and Behavioural Disorders (ICD-10), it surely remains challenging for the clinician to distinguish between religious delusions as a potential expression of a psychiatric disorder, mystical experience, and positive religious coping strategies. Disturbances that have a religious dimension should not by default be viewed as pathological. The helium will not hold the book up for the duration of the exhibition. Visitors will be able to witness the weight of the book eventually bringing the balloons down to earth.