This essay's subject matter is part of the labour market problem. As for all markets the equilibrium position is characterized by two aspects: what price will prevail and what is the volume transacted? For a complex of markets the prices and transactions of each compartment characterize equilibrium. In this essay only the transactions aspect will be discussed; it may also be called the allocation problem: which worker will be allocated which job? The number of workers will be assumed equal to the number of jobs. Here workers, as in the American and possibly other censuses, stands for all who work, independents as well as employees. Workers are characterized by personality traits, including factors such as years of schooling completed, manual dexterity, IQ, social intelligence (i.e. the ability to deal with people), etc. The number of independent personality traits is hardly known, since many concepts used may partly overlap. Jobs are characterized by a set of requirements which personality traits have to satisfy in order that the job can be done (more or less) satisfactorily. Some personality traits may be relevant to several job requirements, for instance, zeal or kindness; other personality traits may be irrelevant.