The concept of aggression has many contents. As a result the operational definition of different research workers varies considerably. We have confined ourselves to aggression as an emotion. The possibilities of quantifying emotions are still insufficient and the danger of over-generalization is still present. The concept of aggression has a sur-plus-meaning and can not be detached from the thinking model of the investigator. Derived activities such as itching and scratching in their relation to motor discharge of aggressive emotions in normal human beings are discussed. The two working hypotheses within the psychoanalytical thinking model, namely abreaction of strangulated affects and the pensée opératoire, are critically reviewed. In our opinion repressed aggressive feelings in the patient-doctor relationship and analogous relationships can lead to the onset of psychosomatic symptoms.