cessful career. His
introductory address was marked by brilliant eloquence, and his lectures
soon acquired fame. He wrote for his pupils on the laws of motion, on
fortifications, on sun-dials, on mechanics, and on the celestial globe:
some of these papers are now lost, others have been printed during the
present century.

Kepler sent him a copy of his new book, _Mysterium Cosmographicum_, and
Galileo, in thanking him for it, writes him the following letter:

"I count myself happy, in the search after truth, to have so great an
ally as yourself, and one who is so great a friend of the truth itself.
It is really pitiful that there are so few who seek truth, and who do
not pursue a perverse method of philosophizing. But this is not the
place to mourn over the miseries of our times, but to congratulate you
on your splendid discoveries in confirmation of truth. I shall read your
book to the end, sure of finding much that is excellent in it. I shall
do so with the more pleasure, because _I have been for many years an
adherent of the Copernican system_, and it explains to me the causes of
many of the appearances of nature which are quite unintelligible on the
commonly accepted hypothesis. _I have collected many arguments for the
purpose of refuting the latter_; but I do not venture to bring them to
the light of publicity, for fear of sharing the fate of our master,
Copernicus, who, although he has earned immortal fame with some, yet
with very many (so great is the number of fools) has become an object of
ridicule and scorn. I should certainly venture to publish my
speculations if there were more people like you. But this not being the
case, I refrain from such an undertaking."

Kepler urged him to publish his arguments in favor of the Copernican
theory, but he hesitated for the present, knowing that his declaration
would be received with ridicule and opposition, and thinking it wiser to
get rather more firmly seated in his chair before encountering the storm
of controversy. The six years passed away, and the Venetian Senate,
anxious not to lose so bright an ornament, renewed his appointment for
another six years at a largely increased salary.

Soon after this appeared a new star--the _stella nova_ of 1604--not the
one Tycho had seen--that was in 1572--but the same that Kepler was so
much interested in. Galileo gave a course of three lectures upon it to a
great audience. At the first the theatre was overcrowded, so he had to