al
predictions, and his astronomical machine for exhibiting the motions
of the stars was also meant to be helpful in the construction of
astrological tables. It must not be forgotten, however, that in his
time the best astronomers, like Tycho Brahe and even Kepler, had not
entirely given up the idea of the influence of the stars over man's
destiny.

As regards other sciences, there are details of information that may
appear quite as superstitious as the belief in astrology. Kircher, for
instance, accepted the idea of the possibility of the transmutation of
metals. It is to be said, though, that all mankind were convinced of
this possibility, and indeed not entirely without reason. All during
the nineteenth century scientists believed very firmly in the absolute
independence of chemical elements and their utter
non-interchangeability. As the result of recent discoveries, however,
in which one element has apparently been observed giving rise to
another, much of this doctrine has come to be considered as
improbable, and now the idea of possible transmutation of {127} metals
and other chemical elements into one another appears not so absurd as
it was half a century ago.

Any one who will take up a text-book of science of a century ago will
find in it many glaring absurdities. It will seem almost impossible
that a scientific thinker, in his right senses, could have accepted
some of the propositions that are calmly set down as absolute truths.
Every generation has made itself ridiculous by knowing many things
"that are not so," and even ours is no exception. Father Kircher was
not outside this rule, though he was ahead of his generation in the
critical faculty that enabled him to eliminate many falsities and to
illuminate half-truths in the science of his day.

Undoubtedly the most interesting of Father Kircher's scientific books
is his work On the Pest, with some considerations on its origin, mode
of distribution, and treatment, which about the middle of the
seventeenth century gathered together all the medical theories of the
times as to the causation of contagious disease, discussed them with
critical judgment and reached conclusions which anticipate much of
what is most modern in our present-day medicine. It is this work of
Father Kircher's that is now most often referred to, and very
deservedly so, because it is one of the classics which represents a
landmark in knowledge for all time. It merits a place beside such