268 KNOWLEDGE HAS DIMINISHED DISEASE. 



ence of bad air, crowding, and imperfect food, in 

 abridging life. Even in the best-managed commu- 

 nities, the number, not only of the sick of all ages, 

 but of those who are cut off in early youth, is so 

 prodigious as to show that we are far from having 

 arrived at the maximum of health of which the race 

 is susceptible ; while the advance we have already 

 nade gives us every reason to hope that, by per- 

 severance and the extension of our knowledge, we 

 may continue to improve for many centuries to 

 come. 



The progress of knowledge, and the increasing 

 ascendency of reason, have already delivered us 

 from many scourges which were regarded by our 

 forefathers as unavoidable dispensations of an in- 

 scrutable Providence. In the days of the ancient 

 Romans, their capital and territories were frequently 

 almost depopulated by visitations of plague and 

 pestilence, from which the present generation is, 

 by a stricter observance of the conditions of health, 

 entirely exempted. In London, in like manner, the 

 same contempt of cleanliness, ventilation, and com- 

 fort which was so fatal to the Romans produced simi- 

 lar results, and swept off its thousands and tens of 

 thousands, till a fortunate disaster the great fire 

 came in the place of knowledge, and, by destroying 

 the crowded lanes and other sources of impurity, 

 which man had shown himself so little solicitous to 

 remove, procured for its inhabitants a perfect and per- 

 manent immunity from one of the deadliest forms of 

 disease, and taught them the grand practical truth, 

 that such awful visitations are not wanton inflictions 

 of a vengeful Providence, but the direct consequences 

 of our non-observance of those conditions by which 

 the various vital functions are regulated, and by 

 conforming to which alone health can be preserved. 

 Accordingly, by greater attention to proper food, 

 cleanliness, and pure air, London, with its gigantic 

 population, now flourishes in comparative security, 



