. "Many primary and
secondary planets," they might say, "are enumerated in these tables,
which exist no longer. Their positions are assigned with such precision
that we may assure ourselves that there is nothing in their place at
present but the blue ether. Where one star is visible to us, these
documents represent several thousands. Some of those which are now
single consisted then of two separate bodies, often distinguished by
different colors, and revolving periodically round a common centre of
gravity. There is nothing analogous to them in the universe at present;
for they were neither fixed stars nor planets, but seem to have stood in
the mutual relation of sun and planet to each other. We must conclude,
therefore, that there has occurred, at no distant period, a tremendous
catastrophe, whereby thousands of worlds have been annihilated at once,
and some heavenly bodies absorbed into the substance of others."

When such doctrines had prevailed for ages, the discovery of some of the
worlds, supposed to have been lost (the satellites of Jupiter, for
example), by aid of the first rude telescope invented after the revival
of science, would not dissipate the delusion, for the whole burden of
proof would now be thrown on those who insisted on the stability of the
system from a remote period, and these philosophers would be required to
demonstrate the existence of _all_ the worlds said to have been
annihilated.

Such popular prejudices would be most unfavorable to the advancement of
astronomy; for, instead of persevering in the attempt to improve their
instruments, and laboriously to make and record observations, the
greater number would despair of verifying the continued existence of the
heavenly bodies not visible to the naked eye. Instead of confessing the
extent of their ignorance, and striving to remove it by bringing to
light new facts, they would indulge in the more easy and indolent
employment of framing imaginary theories concerning catastrophes and
mighty revolutions in the system of the universe.

For more than two centuries the shelly strata of the Subapennine hills
afforded matter of speculation to the early geologists of Italy, and few
of them had any suspicion that similar deposits were then forming in the
neighboring sea. They were as unconscious of the continued action of
causes still producing similar effects, as the astronomers, in the case
above supposed, of the existence of certain heavenly bodies st