Psychiatry is still in need of a concept of emotion, from which affective phenomena can be described and systematically ordered. Recent developments in psychology and philosophy show a lively theoretical interest in emotions. It is to be expected, therefore, that the results of empirical research will soon penetrate into psychiatric theory and practice. This article focusses on three themes which play a major role in conceptualizing affective phenomena: the relation between bodily and psychic aspects of affectivity, the presumed cognitive `causation' of emotions and the connection between emotional expression and dispositions (habits, personality-traits). In discussing these themes the psychology of the greek philosopher Aristotle is taken as a point of departure. It is argued that classificatory problems related to the affective disorders are at least partly a reflection of the close entwinement of the level of symptoms with the level of dispositions.