There are still agnostics, usually of exclusively classical and mathematical education, even among men holding official sanitary administrative positions, who doubt the value of the application of medical knowledge to the extent indicated; and it becomes desirable, therefore, briefly to refer to some results already obtained by the application of preventive and curative medicine. _The Past Achievements of Medicine_ The increasing span of life is scarcely realized as it should be. Addison’s description of the bridge of human life, in his Vision of Mirza, is familiar. Its seventy to a hundred arches support a bridge which is interrupted by broken arches and hidden pitfalls, set very thick at the entrance of the bridge, thinner towards its middle, but multiplied and laid close together towards its further end. Preventive medicine is gradually repairing the broken arches of earlier life; with the prospect of rapid reduction of tuberculosis, of syphilis and gonorrhoea, the removal of pitfalls and the repair of both earlier and middle arches are ensured, if the knowledge we already possess is applied; and although pneumonia and cancer still erode and render unsafe the arches of middle and later adult life, we have already advanced far towards the ideal of euthanasia in old age. I may be excused from quoting English figures, as our vital statistics are more accurate and complete than those hitherto available for the United States. Parenthetically, may I say that it is a continual source of astonishment to me that in some American states death statistics, and in many more states birth statistics should still be so dubious in their quality as to cause hesitation in utilizing them. And this in a country which in other respects combines the highest business qualities with an underlying idealism which emerges in important crises! Between 1871-80 and 1910-12 in England the average expectation of life at birth for males increased from 41.4 to 51.5, for females from 44.6 to 55.4,—an increase within three or four decades of 10 or 11 years in average duration of life. The annual saving of life shown by these figures means that the persons whose lives _each year_ are thus saved in England from premature death, have the prospect of living in the aggregate nearly ten million additional years of life, of which the greater part will be lived during the working period of life.