[5] It is scarcely necessary to say that other classifications of social reform on its more hygienic side may be put forward. Thus W.H. Allen, looking more narrowly at the sanitary side of the matter, but without confining his consideration to the nineteenth century, finds that there are always seven stages: (1) that of racial tutelage, when sanitation becomes conscious and receives the sanction of law; (2) the introduction of sanitary comfort, well-paved streets, public sewers, extensive waterworks; (3) the period of commercial sanitation, when the mercantile classes insist upon such measures as quarantine and street-cleaning to check the immense ravages of epidemics; (4) the introduction of legislation against nuisances and the tendency to extend the definition of nuisance, which for Bracton, in the fourteenth century, meant an obstruction, and for Blackstone, in the eighteenth, included things otherwise obnoxious, such as offensive trades and foul watercourses; (5) the stage of precaution against the dangers incidental to the slums that are fostered by modern conditions of industry; (6) the stage of philanthropy, erecting hospitals, model tenements, schools, etc.; (7) the stage of socialistic sanitation, when the community as a whole actively seeks its own sanitary welfare, and devotes public funds to this end. (W.H. Allen, "Sanitation and Social Progress," _American Journal of Sociology_, March, 1903.) [6] Dr. F. Bushee has pointed out ("Science and Social Progress," _Popular Science Monthly_, September, 1911) that there is a kind of related progression between science and practice in this matter: "The natural sciences developed first, because man was first interested in the conquest of nature, and the simpler physical laws could be grasped at an early period. This period brought an increase of wealth, but it was wasteful of human life. The desire to save life led the way to the study of biology. Knowledge of the physical environment and of life, however, did not prevent social disease from flourishing, and did not greatly improve the social condition of a large part of society. To overcome these defects the social sciences within recent years have been cultivated with great seriousness. Interest in the social sciences has had to wait for the enlarged sympathies and the sense of solidarity which has appeared with the growing interdependence of dense populations, and these conditions have been dependent upon the advance of the other sciences. With the cultivation of the social sciences, the chain of knowledge will be complete, at least so far as the needs which have already appeared are concerned. For each group of sciences will solve one or more of the great problems which man has encountered in the process of development. The physical sciences will solve the problems of environment, the biological sciences the problems of life, and the social sciences the problems of society."