uniform kindness in the face of great rudeness and
ingratitude. He begged him to come “as
a welcome friend,” though Kepler, very touchy
on the subject of his own astronomical powers, was
afraid he might be regarded as simply a subordinate
assistant. An arrangement had been suggested by
which Kepler should obtain two years’ leave
of absence from Gratz on full pay, which, because
of the higher cost of living in Prague, should be supplemented
by the Emperor; but before this could be concluded,
Kepler threw up his professorship, and thinking he
had thereby also lost the chance of going to Prague,
applied to Maestlin and others of his Tuebingen friends
to make interest for him with the Duke of Wurtemberg
and secure the professorship of medicine. Tycho,
however, still urged him to come to Prague, promising
to do his utmost to secure for him a permanent appointment,
or in any event to see that he was not the loser by
coming. Kepler was delayed by illness on the
way, but ultimately reached Prague, accompanied by
his wife, and for some time lived entirely at Tycho’s
expense, writing by way of return essays against Reymers
and another man, who had claimed the credit of the
Tychonic system. This Kepler could do with a
clear conscience, as it was only a question of priority
and did not involve any support of the system, which
he deemed far inferior to that of Copernicus.
The following year saw friction between the two astronomers,
and we learn from Kepler’s abject letter of apology
that he was entirely in the wrong. It was about
money matters, which in one way or another embittered
the rest of Kepler’s life, and it arose during
his absence from Prague. On his return in September,
1601, Tycho presented him to the Emperor, who gave
him the title of Imperial Mathematician, on condition
of assisting Tycho in his calculations, the very thing
Kepler was most anxious to be allowed to do: for
nowhere else in the world was there such a collection
of good observations sufficient for his purpose of
reforming the whole theory of astronomy. The
Emperor’s interest was still mainly with astrology,
but he liked to think that his name would be handed
down to posterity in connection with the new Planetary
Tables in the same way as that of Alphonso of Castile,
and he made liberal promises to pay the expenses.
Tycho’s other principal assistant, Longomontanus,
did not stay long after giving up the Mars observations
to Kepler, but instead of working at the new lunar
theory, suddenly left to take up a professorship of
astronomy in his native Denmark. Very shortly
afterwards Tycho himself died of acute distemper;
Kepler began to prepare the mass of manuscripts for
publication, but, as everything was claimed by the
Brahe family, he was not allowed to finish the work.
He succeeded to Tycho’s post of principal mathematician
to the Emperor, at a reduced official salary, which
owing to the emptiness of the Imperial treasury was
almost always in arrear. In order to meet his
expenses he had recourse to the casting of nativities,
for which he gained considerable reputation and received
very good pay. He worked by the conventional rules
of astrology, and was quite prepared to take fees
for so doing, although he had very little faith in
them, preferring his own fanciful ideas.