isease. He is sure that they are carried by flies, for instance, and
that they may be inoculated by the stings of such insects as fleas or
mosquitoes. He even gives some examples that he knew of in which this
was demonstrated. Still more striking is his insistence on the fact
that such a contagious disease as pest may be carried by cats and dogs
and other domestic animals. The cat seemed to him to be associated
with special danger in this matter, and he gives an example of a
nunnery which had carefully protected itself against possible
infection, but had allowed a cat to come in, with the result that some
cases of the disease developed.

{130}

An interesting bit of discussion is to be found in the chapter in
which Father Kircher takes up the consideration of the problem whether
infectious disease can ever be produced by the imagination. He is
speaking particularly of the pest, but there is more than a suspicion
that under the name pest came at times of epidemics many of our modern
contagious diseases. Father Kircher says that there is no doubt that
worry plays an important role in predisposing persons to take the
disease. He does not consider, however, that it can originate of
itself, or be engendered in the person without contact with some
previous case of pest. With regard to the question of predisposition
he is very modern. He points out that many persons do not take the
disease, because evidently of some protective quality which they
possess. He is sure, too, that the best possible protection comes from
keeping in good, general health.

A curious suggestion is that with regard to the grave-diggers and
undertakers. It has often been noted in Italy, so Father Kircher
asserts, that these individuals as a rule did not succumb to the
disease, notwithstanding their extreme exposure, when the majority of
the population were suffering from it. Toward the end of the epidemic,
however, at the time when the townspeople were beginning to rejoice
over its practical disappearance, it was not unusual to have these
caretakers of the dead brought down with the disease--often, too, in
fatal form. Father {131} Kircher considers that only strong and
healthy individuals would take up such an occupation. That the
satisfaction of accomplishing a large amount of work and making money
kept them in good health. Later on, however, as the result of overwork
during the time of the epidemic and also of discouragement because
they saw the en