Émile Durkheim (1858–1917) saw society as a functioning organism. Functionalism concerns "the effort to impute, as rigorously as possible, to each feature, custom, or practice, its effect on the functioning of a supposedly stable, cohesive system," The chief form of social conflict that Durkheim addressed was crime. Durkheim saw crime as "a factor in public health, an integral part of all healthy societies." The collective conscience defines certain acts as "criminal." Crime thus plays a role in the evolution of morality and law: " implies not only that the way remains open to necessary changes but that in certain cases it directly prepares these changes."