Moreover, there is one class--large, growing in importance, and an essential element in modern civilisation--about whose domestic expenditure we have no scientific knowledge at all. This is the class which may be named "the routine brain-workers," the people who as clerks, book-keepers, salesmen, typists, &c., are responsible for the routine administration of modern commerce. They have been compared to the nervous system, for like that system in the animal body they serve for the communication and the mechanical record of the life of the community on its industrial side. With them may be classed elementary school-teachers, reporters, and the lower ranks of the Civil Service, though I should not be prepared to say that some of these--especially the teachers--ought to be regarded as performing only routine brain-work. But all these workers can be conveniently studied together in that their labour is carried on under somewhat similar conditions--it is sedentary, highly regimented, exhausting to the brain and nervous system, and is generally remunerated by a fixed salary, &c. They earn an income larger than that of the manual labourer, but considerably less as a general rule than that of the professional man. There is a total absence of information as to the domestic expenditure of this class. It is sometimes declared that its less well-paid members suffer as severely from poverty as do sections of the working-class, and that the poor clerk is really much more to be pitied than the well-to-do trade unionist, the skilled manual worker. But no one has yet attempted to test the truth of this view by the only scientific means, namely, by the collection of precise details as to the domestic expenditure of the routine brain-working class, showing what sums are spent on house-room, food, clothing, &c., and what kind of accommodation is obtained for the money spent. In short, the investigation of domestic expenditure has never yet been carried out in a purely scientific spirit solely for the sake of the resultant knowledge. It has always been undertaken with some special practical problem in view, and is consequently always fragmentary and frequently biassed. Yet if it is important to know how the wealth of the country is produced, it is of equal importance to know how it is consumed, and that whether the consumption takes the form of porridge and flannelette for the child of a dock-labourer, of drink and admission to a football match for the miner or cotton-operative, or of a gardener, and a holiday in Switzerland for the hard-working doctor or stockbroker. Domestic expenditure should be investigated as impartially by the economist as are the variations of plants or animals by the biologist. His one aim should be the discovery and statement of truth, as complete and as unbiassed as he can make it.