Unlike neurologists, affect not the brain is the object of psychiatrists' specialist medical expertise. Defined as feelings, emotions and agitations, affect integrates human responses and drives brain and body changes, thinking, perceiving, relating and acting. In no particular order, it depends on genes, evolution, culture, physiology, personal experience, social history, chance, meaning, the environment and a sense of self and others. Disturbance in any (combination) of these may lead to psychopathology, the understanding and treatment of which demands biomedical training, empathic curiosity about the human soul, a pluralist perspective, tolerance of anxiety and engagement with public perceptions, policies and ideologies.