COSMOS, VOL. II - World eBook Library

698 COSMOS.
of the world now appeared objectively, and as it were archi-
tecturally, in its simple grandeur ; but it remained for Isaac
Newton to disclose the play and connection of the internal
forces which animate and preserve the system of the universe.
We have already often remarked in the history of the gradual
development of human knowledge, that important but
apparently accidental discoveries, and the simultaneous appearance
of many great minds, are crowded together in a
short period of time ; and we find this phenomenon most
of the seventeenth
strikingly manifested in the first ten years
century ; for Tycho Brahe (the founder of modern astronomic^
calculations), Kepler, Galileo, and Lord Bacon, were cotemporaries.
All these, with the exception of Tycho Brahe, were
enabled, in the prime of life, to benefit by the labours of Descartes
and Fermat. The elements of Bacon's Instauratio
Magna appeared in the English language in 1605, fifteen years
before the Novum Organon. The invention of the telescope, and
the greatest discoveries in physical astronomy (viz., Jupiter's
satellites, the sun's spots, the phases of Venus, and the
remarkable form of Saturn), fall between the years 1609 and
1612. Kepler's speculations on the elliptic orbit of Mars,*
were began in 1601, and gave occasion, eight years after, to
the completion of the work entitled Astronomia nova sett
Physica celestis.
"
By the study of the orbit of Mars,"
writes
"
Kepler, we must either arrive at a knowledge of the
secrets of astronomy, or for ever remain ignorant of them.
I have succeeded, by untiring and continued labour, in subjecting
the inequalities of the movement of Mars to a natural
law." The generalization of the same idea led the highly-
gifted mind of Kepler to the great cosmical truths and presentiments
which, ten years later, he published in his work
entitled Harmonices Mundi "
libri quinque. I believe," he
well observes in a letter to the Danish astronomer Longo-
rotatory and progressive movement of the terrestrial planet in its orbit,
has freed the original system of Copernicus from the assumption of a
declination-movement, or a so-called third movement of the earth (De Revolut.
orb. cod., lib. i. cap. 11, triplex motus telluris.) The parallelism,
of the earth's axis is maintained in the annual revolution round the
sun, in conformity with the law of inertia, without the application
correcting epicycle.
* Delambre, Hist, del'Astronomic ancienne, t. ii. p. 381.
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