"What, then, can the Government do? Extermination of rats is impossible; disinfection on a large scale is impracticable; evacuation of villages cannot be done voluntarily on any universal scale; the Government will not apply compulsion, and such evacuation is quite useless without a rigid cordon of police or military that will prevent communication between one infected village and others not yet infected. A cordon, it has been proved over and over again, cannot be maintained; the native who wishes to pass it has only to present some official with a cautious rupee. Extermination of rats in an Asiatic country has often failed; but here is without a shadow of doubt the key to the problem. The methods formerly adopted had been to give a capitation grant for every rat brought to the appointed place, and before long it was found, for instance in Bombay, that an extensive trade had grown up in the breeding of rats, whereby, at a few annas apiece from the Government, many families were able to sustain a comfortable existence.... But since sentence on the rat-flea has been pronounced for the murder of 7,000,000 persons and over, the best method for his extermination will not be far off. "It is often debated whether even half-measures are worth being continued. Professor W. J. Simpson, in his exhaustive monograph on the plague, and in 1907 in his _Croonian Lectures_, has shown how in history epidemics of plague have come and gone in different countries with long intervals between them, often of one hundred and thirty to one hundred and fifty years. In the eighteenth century, for instance, India seems to have been almost free of the plague, but early in the seventeenth century it suffered severely. The present epidemic is assuming, as far as we can trust previous records, unprecedented proportions; probably after a few years it will die out again. "An occasional cynic may argue that, since we have saved so many thousands of lives annually from famine and wars, it may be just as well to let the plague take their place. To such a pessimistic and inhuman conclusion it is impossible for one moment to submit. It may be that for economic reasons some parts of the Indian Empire would be happier if their population were less dense; but it does not follow that we should allow Death to stalk uninterrupted, unopposed, and apparently without limit, throughout the country. Economics apart, we may yet be absolutely convinced, whether as doctors or as statesmen, that it is our mission, our duty, to protect the populations included under British rule to the best of our ability against every scourge as it may arise; and therefore it is urgent that such measures as we have be pushed forward with the utmost vigour."