provided it
received the sanction of the Emperor. This was readily given, and
Kepler, in 1629, removed with his family from Linz to Sagan, in Silesia.
The Duke of Friedland treated him with great kindness and liberality,
and through his influence he was appointed to a professorship in the
University of Rostock. Though Kepler was permitted to retain the pension
bestowed upon him by the late Emperor Rudolph, he was unable after his
removal to Silesia to obtain payment of it, and there was a large
accumulation of arrears. In a final endeavour to recover the amount
owing to him he travelled to Ratisbon, and appealed to the Imperial
Assembly, but without success. The fatigue which Kepler endured on his
journey, combined with vexation and disappointment, brought on a fever,
which terminated fatally. He died on November 15, 1630, when in the
sixtieth year of his age, and was interred in St. Peter's churchyard,
Ratisbon.

Kepler was a man of indomitable energy and perseverance, and spared
neither time nor trouble in the accomplishment of any object which he
took in hand. In thinking over the form of the orbits of the planets, he
writes: 'I brooded with the whole energy of my mind on this
subject--asking why they are not other than they are--the number, the
size, and the motions of the orbits.' But many fanciful ideas passed
through Kepler's imaginative brain before he hit upon the true form of
the planetary orbits. In his 'Mysterium Cosmographicum' he asserts that
the five kinds of regular polyhedral solids, when described round one
another, regulated the distances of the planets and size of the
planetary orbits. In support of this theory he writes as follows: 'The
orbit of the Earth is the measure of the rest. About it circumscribe a
dodecahedron. The sphere including this will be that of Mars. About
Mars' orbit describe a tetrahedron; the sphere containing this will be
Jupiter's orbit. Round Jupiter's describe a cube; the sphere including
this will be Saturn's. Within the Earth's orbit inscribe an icosahedron;
the sphere inscribed in it will be Venus's orbit. In Venus inscribe an
octahedron; the sphere inscribed in it will be Mercury's.'

The above quotation is an instance of Kepler's wild and imaginative
genius, which ultimately led him to make those sublime discoveries
associated with planetary motion which are known as 'Kepler's Laws.'

He describes himself as 'troublesome and choleric in politics and
domestic matters;'