CHAPTER VII
THE CAUSES OF THESE FEVERS

All these phenomena were known to the public and lay open
to the eye. But as to their causes and how they came to pass,
there was great disagreement and dispute among the doctors,
and various theories were held. Some asserted that an acute
inflammatory condition was the cause, others plethora (of the
humors), others intranspiration of bodies,?' others  alleged
some occult property.  Hence each doctor applied his own rem—
edies in accordance with his theory, which led to jesting at the
expense of our profession, because so much disagreement could
not be concealed from the public. But since these fevers were
wide—spread, and were common to many persons at the same
time, we must conclude that they had at that time a common
cause, and that it was mainly contracted from the air, which
seems reasonable enough. For, in the year 1528, there was
first a winter of south winds and much rain, and in the spring
many rivers overflowed their banks, with us, for instance, the
Adige and the Po, and others elsewhere. At the same time
there were mists which shrivelled most of the buds on the trees,
especially the olives. From these causes we may believe that
the principle (primary agent) of these fevers arose. But those
which now appear sporadically have their special cause in our—
selves in whom they first occur, and they take on a putrefaction
of the same sort and exactly like that putrefaction which original—
ly was common to many persons and had its origin in the air.
Now this contagion, in comparision with those that are truly
pestilent, seems rather mild, and is not contracted quickly, does
not leave fomes behind, and is not carried to a distant object,
but works slowly and only through actual handling of a sick
person. We must therefore conclude that its germs are not
very keen, and that they have not the strong and well—worked
combination described above, but are more suited to be altered
easily, and not to adhere, as others do which leave fomes be—

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