CHAPTER II
TREATMENT DIRECTED TO THE PRINCIPLES OF CONTAGION

After making the observations recommended above, remember
that there are three essential points to which you must direct
your undivided attention. First, the principles in which the
putrefaection has its beginning and source; secondly, the sub—
stance which is on the way to be, and is already beginning to
be, infected; thirdly, the substance which has already been cor—
rupted and cannot again be restored to a normal condition.
The principles are, as I have said, sometimes common to other
diseases that consist in putrefaction, sometimes they are peculiar
to contagious diseases. Common principles are: plethora,
obstruction and malignancy of the humors, and the like. Pecu—
liar principles are the actual germs of the contagions. For
there is nothing to prevent a man whose health is absolutely
good, whose humors etc. are in good order, from contracting
a contagion from another person. 'Therefore, if the common
principles only are present, we need say no more, and nothing :
more need be done than what the doctors prescribe when there
are present plethora, obstructions, and other conditions of that
sort. But when there are present the principles (primary
agents) peculiar to contagions, then there is need of great care
and diligence. For if you are at once able to destroy, expel,
or break up the germs themselves, then the disease will not
progress further. So study its beginnings with the greatest
eare, if you have the opportunity; but if you cannot do this,
remember that in the whole course of the disease you must pay
incessant attention to the germs. For this you need manifold
resources, for you must bring now one method, now another to
bear on those germs. For they may be blotted out and, so to
speak, slain, expelled, or broken and altered, or driven back.
But it is not always possible to employ all these means, nor is
it advisable, but you may employ now one method now another,
now several at once, as the disease itself or the occasion and the
rest of the conditions demand.

191