ld have to
learn that, although London contains tenfold the inflammable matter that
it did in 1666; though, not content with filling our rooms with woodwork
and light draperies, we must needs lead inflammable and explosive gases
into every corner of our streets and houses, we never allow even a
street to burn down. And if he asked how this had come about, we should
have to explain that the improvement of natural knowledge has furnished
us with dozens of machines for throwing water upon fires, any one of
which would have furnished the ingenious Mr. Hooke, the first "curator
and experimenter" of the Royal Society, with ample materials for
discourse before half a dozen meetings of that body; and that, to say
truth, except for the progress of natural knowledge, we should not
have been able to make even the tools by which these machines are
constructed. And, further, it would be necessary to add, that although
severe fires sometimes occur and inflict great damage, the loss is very
generally compensated by societies, the operations of which have been
rendered possible only by the progress of natural knowledge in the
direction of mathematics, and the accumulation of wealth in virtue of
other natural knowledge.

But the plague? My Lord Brouncker's observation would not, I fear, lead
him to think that Englishmen of the nineteenth century are purer in
life, or more fervent in religious faith, than the generation which
could produce a Boyle,[40] an Evelyn,[41] and a Milton. He might find
the mud of society at the bottom, instead of at the top, but I fear that
the sum total would be as deserving of swift judgment as at the time of
the Restoration.[42] And it would be our duty to explain once more, and
this time not without shame, that we have no reason to believe that it
is 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, an