SECTION I. 
SANITARY SCIENCE AND HYGIENE. 
PRESIDENTIAL ADDRESS. 
By Sir T. N. Firzceratp, C.B., F.R.C.8.1. 
THE NATURE OF DISEASE. 
WHEN, some months ago, I received an invitation from 
the Secretary to take the chair at the Section of Hygiene 
and Sanitary Science of this Association, I at first felt 
dubious about accepting it. It seemed to me, on the face 
of it, rather incongruous that one whose whole life has 
been almost exclusively devoted to the practice of an art 
little concerned with the dissemination of sanitary know- 
ledge should fill the office of Chairman at your meetings; 
indeed, I was disposed to decline your courteous proposal. 
However, on reflection, my impulse changed, especially 
when I called to mind how essentially of late years the 
observance of the strictest hygienic rules had become 
necessary to the highest developments of surgery. I 
remembered, too, with the keen enjoyment a soldier feels 
in relating the tales of his various encounters, the con- 
tests we had had with the lay authorities who control our 
institutions, about the expense and inconvenience of 
introducing antiseptics; what struggles we engaged in with 
those who at the time met our efforts with the terms 
“fads” and ‘nonsense.’ Would they not now blush 
could they be reminded of their former obstinacy, and the 
contempt they expressed when we endeavoured to impress 
upon them the imperativeness of isolation in offensive and 
infective cases, and the benefit of a sweeter atmosphere 
for the others? Many of our former opponents are, alas! 
dead, but still a few remain who, in other matters— 
medical and elective—are as irreconcilable and as opposed 
to change as ever. These and other memories returning, 
I decided to accept your offer. 
Then came another difficulty—the choice of a subject. 
For the address which inaugurated the office would have 
