We discover, moreover, from our view of the past, that the developments of tenacity of life and of vital power have been comparatively rapid in their course when they have once commenced.  There is nothing discoverable to us that would lead to the conception of a human civilisation extending back over two hundred generations; and when in these generations we survey the actual effect of civilisation, so fragmentary and overshadowed by persistent barbarism, in influencing disease and mortality, we are reduced to the observation of at most twelve generations, including our own, engaged, indirectly or directly, in the work of sanitary progress.  During this comparatively brief period, the labour of which, until within a century, has had no systematic direction, the changes for good that have been effected are amongst the most startling of historical facts.  Pestilences which decimated populations, and which, like the great plague of London, destroyed 7,165 people in a single week, have lost their virulency; gaol fever has disappeared, and our gaols, once each a plague-spot, have become, by a strange perversion of civilisation, the health spots of, at least, one kingdom.  The term, Black Death, is heard no more; and ague, from which the London physician once made a fortune, is now a rare tax even on the skill of the hardworked Union Medical Officer.

From the study of the past we are warranted, then, in assuming that civilisation, unaided by special scientific knowledge, reduces disease and lessens mortality, and that the hope of doing still more by systematic scientific art is fully justified.

I might hereupon proceed to my project straightway.  I perceive, however, that it may be urged, that as mere civilising influences can of themselves effect so much, they might safely be left to themselves to complete, through the necessity of their demands, the whole sanitary code.  If this were so, a formula for a city of health were practically useless.  The city would come without the special call for it.

I think it probable the city would come in the manner described, but how long it would be coming is hard to say, for whatever great results have followed civilisation, the most that has occurred has been an unexpected, unexplained, and therefore uncertain arrest of the spread of the grand physical scourges of mankind.  The phenomena have been suppressed, but the root of not one of them has been touched.  Still in our midst are thousands of enfeebled human organisms which only are comparable with the savage.  Still are left amongst us the bases of all the diseases that, up to the present hour, have afflicted humanity.