Ignorant men may sneer at the pretensions of sanitary science; weak and timorous men may hesitate to commit themselves to its principles, so large is their application; selfish men may shrink from the labour of change, which its recognition must entail; and wicked men may turn indifferently from considering that which concerns the health and happiness of millions of their fellow-creatures; but in the great objects which it proposes to itself, in the immense amelioration which it proffers to the physical, social, and, indirectly, to the moral conditions of an immense majority of our fellow creatures, it transcends the importance of all other sciences; and, in its beneficent operation, seems to embody the spirit, and to fulfil the intentions, of practical Christianity. With such noble ideals, what measure of success crowned their efforts and those of their successors? The earlier history I can only briefly mention, as we are chiefly concerned today with events since 1869. To understand these events, however, one must understand the forces which had been accumulating and increasing in power in earlier years, and which rendered possible the rapid public health progress experienced in the fourth quarter of the nineteenth and the first quarter—so far as it has passed—of the twentieth century. _Laissez Faire Economic Teaching_ Historians in future generations will refer to the second half of the eighteenth and the first half of the nineteenth century as the period of unmitigated industrialism, of associated rapid increase of urban at the expense of rural life, and of the most extreme manifestation of _laissez faire_ economic science. The older semi-paternal system of interference with the economic life of the people by King and Parliament, was replaced, under the influence of Adam Smith, Malthus, James Mill, and other teachers, by inaction based on the view that in old countries poverty is the natural and inevitable result of pressure of population on means of subsistence, and that any interference with freedom of competition in obtaining work or employing workers is useless or mischievous. A similar view found expression in President Jefferson’s dictum: that government is best which governs least; and until the middle of the nineteenth century these views were generally accepted and their influence was dominant. It was assumed that given free competition, enlightened self-interest would incite effort and improvement, encourage self-reliance, and guarantee production and economy.