Mrs. Bosanquet[105] has told us that the most important economic function of the family to-day is its direct control of the prosperity or ruin of nations; for here alone are found in combination the forces which determine the quantity of the population with the forces which determine its quality. To control these forces offers, to say the least, a life-work for countless men and women. Both parents must safeguard the character of their children's inherited nature; both sexes are more or less directly or remotely concerned in the provision of a suitable environment for human lives, infant or adult. Under the circumstances it may well be a matter for surprise that we have been so slow to perceive that the right performance of these duties demands a preliminary study of the art of preserving health and promoting progress, and we marvel at the placid spirit of content which has sanctioned the conversion into a stronghold of empiricism, the very place where a sound knowledge of progressive sanitary science is of primary importance. In the book to which reference has been already made, Mrs. Bosanquet also enumerates the causes which in her opinion militate most actively against the continuance of family life at the present day. Among others she mentions evasion of responsibility, self-indulgence (with which we are very familiar), reliance upon external sources of maintenance, and the unequal distribution among the members of a family of the burden of support. Further, she refers to the unfortunate failure among parents to realise that the old Roman customs of parental possession and filial submission are out of date to-day, and calls upon the wise guardian to substitute others which lead to loyalty and love. The new movement for a study of the characteristics of childhood and adolescence should materially contribute to the realisation that this parental attitude of dominant authority must be now associated with and modified by a more balanced understanding of the phases of youthful development and of the intricacies of individual temperament. Convenience has hitherto encouraged the customary regulation of a group of young lives as if they were one and the same individual, no allowance being made for variation in character or in age, in propensities or in health. Each nursery party or infant school serves to illustrate the point. Individual tendencies to cold or to fatigue, to nerve storms or to indolence; individual capacities in diet, occupation or exercise, must be intelligently respected if potentialities are to become actualities.