Claims that the individual mind is capable of classification and they seek the origin of the 'classificatory function' in society. This title argues that the mode of classification is determined by the form of society and that the notions of space, time, hierarchy, number, class and other such cognitive categories are products of society. 'This is a significant essay because it is the most unqualified expression of its authors' grand idea that the origins and meaning of mental categories are to be sought in the organisation of societies.' - The Times Literary Supplement