Quite a few people take good health so much for granted that when sick they are likely to consider their disease almost a personal affront. The familiar "Why did I become ill?" is usually inspired more by resentment than by curiosity and has a poignant ring that increases with the seriousness of the malady. When dealing with incurable conditions, the question becomes altogether devastating, since the frustrated physician realizes how little is known of the selective mechanisms that single out one particular victim from a large crowd of more fortunate persons.
This remains disconcertingly true even in the specific case of an illness developing in members of groups known to be particularly susceptible to it. In fact, even though epidemiologic information has shown that, for instance, irradiated individuals, sufferers of Down's syndrome, and probably also farmers are specially prone to leukemia, clinicians as well as epidemiologists are at a loss