not hold good when the planets are considered individually. Mars is
smaller than the Earth; Uranus smaller than Saturn; Saturn smaller than
Jupiter, and succeeds immediately to a host of planets, which, on
account of their smallness, are almost immeasurable. It is true, the
period of rotation generally increases with the distance from the sun;
but it is in the case of Mars slower than in that of the Earth, and
slower in Saturn than in Jupiter."[209] "_Our knowledge of the primeval
ages of the world's physical history does not extend sufficiently far to
allow of our depicting the present condition of things as one of
development._"[210]

Sir David Brewster adds his testimony as follows: "Geology does not
pretend to give us any information respecting the process by which the
nucleus of the earth was formed. Some speculative astronomers indeed
have presumptuously embarked in such an inquiry; but there is not a
trace of evidence that the solid nucleus of the globe was formed by
secondary causes, such as the aggregation of attenuated matter diffused
through space; and the _nebular theory_, as it has been called, though
maintained by a few distinguished names, has, we think, been overturned
by arguments which have never been answered. Sir Isaac Newton, in his
four celebrated letters to Dr. Bentley, has demonstrated that the
planets of the solar system could not have been thus formed and put in
motion round a central sun."[211]

4. _Astronomy not only exposes the folly of past cosmogonies, but
demonstrates the impossibility of framing any true theory of creation,
and thus refutes all future cosmogonies._

The grand error of all cosmogonies lies in the arrogant assumption, on
which every one of them must be founded, _that the theorist is
acquainted with all substances, and all forces in the universe_, and
with all the modes of their operation; not only at the present period,
and on this earth, but in all past ages, and in worlds in widely
different, and utterly unknown situations; for, if he be ignorant of any
substance, or of any active force in the universe, his generalization is
avowedly imperfect, and necessarily erroneous. That unknown force must
have had its influence in framing the world. Its omission, then, is
fatal to the theory which neglects it. A theory of creation, for
instance, which would neglect the attraction of gravitation would be
manifestly false. But there are other forces as far reaching, whose
omissio