phenomena, and they consequently must fail when extended to the whole of
Nature. Water by its common operation, as poured down from the
atmosphere in rain and torrents, tends to level and degrade the surface,
and carries the material of the land into the bosom of the ocean. Fire,
on the contrary, in volcanic eruptions usually raises mountains, exalts
the surface, and creates islands even in the midst of the sea. But these
laws are not invariable, as the instances to which we have just referred
prove, and parts of the surface of the globe are sometimes destroyed even
by fire, of which examples may be seen in the Phlegraean fields, and
islands raised by one volcanic eruption have been immerged in the sea by
another. There are, in fact, no accidents in Nature; what we call
accidents are the results of general laws in particular operation, but we
cannot deduce these laws from the particular operation or the general
order from the partial result." Ambrosio said to the stranger: "You
appear, sir, to have paid so much attention to physical phenomena that
few things would give us more pleasure than to know your opinion
respecting the early changes and physical history of the globe, for I
perceive you do not belong to the modern geological schools." The
stranger said, "I have certainly formed opinions or rather speculations
on these subjects, but I fear they are hardly worth communicating; they
have sometimes amused me in hours of idleness, but I doubt if they will
amuse others." I said, "The observations which you have already been so
kind as to communicate to us, on the formation of the travertine, lead us
not only to expect amusement but likewise instruction."

_The Stranger_.--On these matters I had facts to communicate; on the
geological scheme of the early history of the globe there are only
analogies to guide us, which different minds may apply and interpret in
different ways; but I will not trifle with a long preliminary discourse.
Astronomical deductions and actual measures by triangulation prove that