I.] ON IMPROVING NATURAL KNOWLEDGE. 7 



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 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 pre 

 sumptuous to express the belief that, when our knowledge is 

 more complete and our obedience the expression of our know 

 ledge, 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, ana 

 well-being are more abundant with us than with them ? But 



