In connection with his research on popular religion in Morocco, Westermarck encountered ideas and practices that, according to him, would disprove Emile Durkheim's theory of holiness. In particular, he was struck by what he called the sensitiveness of the holy: the fact that holiness (baraka) could be challenged and renegotiated. This chapter explains why Westermarck saw it as a disconfirmation of Durkheim's theory. Durkheim and Westermarck were near contemporaries. Both saw their research as a contribution to the debate on the 'foundations' or 'origins' of morality and religion, at the time considered a philosophical cause celebre. The debate mixed elements from moral or social philosophy and empirical anthropology. Durkheim's account of religious belief agrees with Westermarck's on a number of points, but his fundamental take on religion is different. To a great extent, the conflict between them concerns the question of what one should look for in a study of religion and society.