investigations of Leonardo, it must be admitted that his work in
science remained almost as infertile as that of his great
precursor, Bacon. The really stimulative work of this generation
was done by a man of affairs, who knew little of theoretical
science except in one line, but who pursued that one practical
line until he achieved a wonderful result. This man was
Christopher Columbus. It is not necessary here to tell the trite
story of his accomplishment. Suffice it that his practical
demonstration of the rotundity of the earth is regarded by most
modern writers as marking an epoch in history. With the year of
his voyage the epoch of the Middle Ages is usually regarded as
coming to an end. It must not be supposed that any very sudden
change came over the aspect of scholarship of the time, but the
preliminaries of great things had been achieved, and when
Columbus made his famous voyage in 1492, the man was already
alive who was to bring forward the first great vitalizing thought
in the field of pure science that the Western world had
originated for more than a thousand years. This man bore the name
of Kopernik, or in its familiar Anglicized form, Copernicus. His
life work and that of his disciples will claim our attention in
the succeeding chapter.



IV. THE NEW COSMOLOGY--COPERNICUS TO KEPLER AND GALILEO

We have seen that the Ptolemaic astronomy, which was the accepted
doctrine throughout the Middle Ages, taught that the earth is
round. Doubtless there was a popular opinion current which
regarded the earth as flat, but it must be understood that this