Knudstrup in the year 1546. He died in 1601 at Prague, in
Bohemia. During a considerable portion of his life he found a
patron in Frederick, King of Denmark, who assisted him to build a
splendid observatory on the Island of Huene. On the death of his
patron Tycho moved to Germany, where, as good luck would have it,
he came in contact with the youthful Kepler, and thus, no doubt,
was instrumental in stimulating the ambitions of one who in later
years was to be known as a far greater theorist than himself. As
has been said, Tycho rejected the Copernican theory of the
earth's motion. It should be added, however, that he accepted
that part of the Copernican theory which makes the sun the centre
of all the planetary motions, the earth being excepted. He thus
developed a system of his own, which was in some sort a
compromise between the Ptolemaic and the Copernican systems. As
Tycho conceived it, the sun revolves about the earth, carrying
with it the planets-Mercury, Venus, Mars, Jupiter, and Saturn,
which planets have the sun and not the earth as the centre of
their orbits. This cosmical scheme, it should be added, may be
made to explain the observed motions of the heavenly bodies, but
it involves a much more complex mechanism than is postulated by
the Copernican theory.

Various explanations have been offered of the conservatism which
held the great Danish astronomer back from full acceptance of the
relatively simple and, as we now know, correct Copernican
doctrine. From our latter-day point of view, it seems so much
more natural to accept than to reject the Copernican system, that
we find it difficult to put ourselves in the place of a
sixteenth-century observer. Yet if we recall that the traditional
view, having warrant of acceptance by nearly all thinkers of