Within recent decades an important change has taken place in the scientific view of anxiety (fear), 2 its genesis, and its psychological significance. Writing in 1890, William James (6) stoutly supported the then current supposition that anxiety was an instinctive ('idiopathic') reaction to certain objects or situations, which might or might not represent real danger. To the extent that the instinctively given, predetermined objects of anxiety were indeed dangerous, anxiety reactions had biological utility and could be accounted for as an evolutionary product of the struggle for existence. On the other hand, there were, James assumed, also anxiety reactions that were altogether senseless and which, conjecturally, came about through Nature's imperfect wisdom. But in all cases, an anxiety reaction was regarded as phylogenetically fixed and unlearned. The fact that children may show no fear of a given type of object, e.g., live frogs, during the first year of life but may later manifest such a reaction, James attributed to the 'ripening' of the fear-of-live-frogs instinct; and the fact that such fears, once they have 'ripened,' may also disappear he explained on the assumption that all instincts, after putting in an appearance and, as it were, placing themselves at the individual's disposal, tend to undergo a kind of obliviscence or decay unless taken advantage of and made 'habitual.' 1 This paper, in substantially its present form, was presented before the Monday Night Group of the Institute of Human Relations, Yale University, March 13, 1939.1 Psychoanalytic writers sometimes differentiate between anxiety and fear on the grounds that fear has a consciously perceived object and anxiety does not. Although this distinction may be useful for some purposes, these two terms will be used in the present paper as strictly synonymous.