e are ascribed to the intervention of
demons, ghosts, witches, and other immaterial and supernatural agents.
By degrees, many of the enigmas of the moral and physical world are
explained, and, instead of being due to extrinsic and irregular causes,
they are found to depend on fixed and invariable laws. The philosopher
at last becomes convinced of the undeviating uniformity of secondary
causes; and, guided by his faith in this principle, he determines the
probability of accounts transmitted to him of former occurrences, and
often rejects the fabulous tales of former times, on the ground of their
being irreconcilable with the experience of more enlightened ages.

_Prepossessions in regard to the duration of past time._--As a belief in
the want of conformity in the causes by which the earth's crust has been
modified in ancient and modern periods was, for a long time, universally
prevalent, and that, too, amongst men who were convinced that the order
of nature had been uniform for the last several thousand years, every
circumstance which could have influenced their minds and given an undue
bias to their opinions deserves particular attention. Now the reader
may easily satisfy himself, that, however undeviating the course of
nature may have been from the earliest epochs, it was impossible for the
first cultivators of geology to come to such a conclusion, so long as
they were under a delusion as to the age of the world, and the date of
the first creation of animate beings. However fantastical some theories
of the sixteenth century may now appear to us,--however unworthy of men
of great talent and sound judgment,--we may rest assured that, if the
same misconception now prevailed in regard to the memorials of human
transactions, it would give rise to a similar train of absurdities. Let
us imagine, for example, that Champollion, and the French and Tuscan
literati lately engaged in exploring the antiquities of Egypt, had
visited that country with a firm belief that the banks of the Nile were
never peopled by the human race before the beginning of the nineteenth
century, and that their faith in this dogma was as difficult to shake as
the opinion of our ancestors that the earth was never the abode of
living beings until the creation of the present continents, and of the
species now existing,--it is easy to perceive what extravagant systems
they would frame, while under the influence of this delusion, to account
for the monuments dis