PRESIDENTIAL ADDRESS IN SECTION #H. 
(Sanitary Science and Hygiene). 
ON THE PRACTICAL BASIS OF PREVENTIVE 
MEDICINE. 
By J. ASHBURTON THOMPSON, M.D., D.P.H. 
WE are met for the advancement of science ; and in this section 
for improvement in the branch of knowledge which teaches the 
causation of disease, and the conditions ancillary to disease which 
act by impairing functional efficiency. A sharp distinction is 
thus drawn between the science and the art of sanitation. The 
former regards the phenomena of life, and especially its duration, 
under observed conditions; the latter devises the means, which 
are sometimes political, sometimes mechanical, by which the 
teachings of science may be put into practice, and the circum- 
stances favourable to life be provided or preserved. And I choose 
rather to say that our occupation is to learn the causes of disease 
than to prevent them for reasons which, if they are trite, are yet 
seldom enough mentioned to warrant me in recalling them. If it 
be assumed that the prevention of all diseases is possible, and that 
by preventing all diseases the average duration of life can be 
extended until death by decay become the common course, it 
needs no profound reflection to show that the change could be 
but temporary, that the truce could but serve to reinforce the 
destroyer. Probably the supposition is fallacious, since we are 
in thrall to our ancestors; but, at all events, success in that 
enterprise must ever involve failure. 
If we pass from thought of disease as it affects mankind in 
general, to consider some kinds of disease in relation to some 
sections of mankind, however, it will at once appear that the 
effort to abate them is natural, and may be successful. The 
preventability of some diseases has now been demonstrated. Once 
that knowledge gained, systematic effort to prevent them follows 
of course. Self-preservation is an instinct ; what man desires 
instinctively for himself civilised man desires strongly for others : 
thus he not only avoids injury for himself, but he warns and 
protects his fellows, although nothing of them be known to him 
but their threatened existence. Now, in learning the causes of 
some diseases we have also learned that their introduction to the 
body is for the most part accidental in no unusual sense ; and, 
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