William Carey defines temperament as 'the characteristic way with which the child experiences and responds to environmental stimuli', and he outlines a short but interesting history of the concept—from the Romans and Greeks to the research carried out by Thomas and Chess, from 1956 onwards, resulting in nine normal traits and three clusters. Carey observes how early 20th-century psychology, in contrast with that of previous centuries, emphasized the dominant importance of the environment, with a few exceptions, among them that of Freud, who wrote in 'Analysis Terminable and Interminable': 'each individual ego is endowed from the beginning with its own peculiar dispositions and tendencies'. Carey's suggestions for improving the situation take into consideration various aspects of the problem: promoting an improved understanding of a normal temperament and of the role of the environment; improving and modifying diagnostic criteria; improving education; and, last but not least, confronting the scandal of the frequent and unhealthy partnership between drug companies and physicians.