22 ON IMPROVING 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 fer- 

 vent in religious faith, than the generation which could 

 produce a Boyle, an Evelyn, 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. 

 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 un- 

 swept 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 obedi- 

 ence, we have no plague; because that knowledge is 

 still very imperfect and that obedience yet incomplete, 

 typhoid 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 obedi- 

 ence the expression of our knowledge, London will 

 count her centuries of freedom from typhoid and 

 cholera, as she now gratefully reckons her two hundred 



