Durkheim's theory of punishment is part of his more general theory of law and appears first in probably his most famous work The Division of Labour in Society (1960, first published in 1893), and is then elaborated and changed somewhat, in his article 'Two Laws of Penal Evolution' (1984, first published in 1901)- In The Division of Labour in Society Durkheim analyses the difference between modern industrial society and forms of society which went before it, and his main concern is to locate the sources and type social solidarity - the common feelings, customs and traditions that make people recognize themselves as part of the same society-in the modern industrial state. He takes the specialization, or division of labour to be the most important difference between industrial and pre-industrial societies, and takes other aspects of a society's culture, including its form of law, to be contingent upon whether a society specializes its labour or not.