the improvement of our faith, nor that of our morals, which keeps the
plague from our city; but, again, that it is the improvement of our
natural knowledge.

We have learned that pestilences will only take up their abode among
those who have prepared unswept and ungarnished residences for them.
Their cities must have narrow, unwatered streets, foul with accumulated
garbage. Their houses must be ill-drained, ill-lighted,
ill-ventilated. Their subjects must be ill-washed, ill-fed,
ill-clothed. The London of 1665 was such a city. The cities of the
East, where plague has an enduring dwelling, are such cities. We, in
later times, have learned somewhat of Nature, and partly obey her.
Because of this partial improvement of our natural knowledge and of
that fractional obedience, we have no plague; because that knowledge is
still very imperfect and that obedience yet incomplete, typhus is our
companion and cholera our visitor. But it is not presumptuous to
express the belief that, when our knowledge is more complete and our
obedience the expression of our knowledge, London will count her
centuries of freedom from typhus and cholera, as she now gratefully
reckons her two hundred years of ignorance of that plague which swooped
upon her thrice in the first half of the seventeenth century.

Surely there is nothing in these explanations which is not fully borne
out by the facts? Surely, the principles involved in them are now
admitted among the fixed beliefs of all thinking men? Surely, it is
true that our countrymen are less subject to fire, famine, pestilence,
and all the evils which result from a want of command over and due
anticipation of the course of Nature, than were the countrymen of
Milton; and health, wealth, and well-being are more abundant with us
than with them? But no less certainly is the difference due to the