'It has long been a commonplace observation in the discipline of social anthropology that cultural systems of explanation or accountability [for the occurrence of a misfortune] need to address two distinct issues. In the first place the general kind of misfortune: how and why does it happen? In the second place, the site and time of particular misfortune require explanation: how and why did it happen to this person at this time?... In our own society, where the development of science has shaped so many other cultural institutions, it is sometimes overlooked that this pair of explanations is still required. This is so because it is a central pillar of the Western scientific tradition that the two explanatory systems are unified.'1(p.4).