fronted
with some of the most stupendous problems which have ever engaged
the restless intellect of humanity. The origin and primaeval
constitution of the terrestrial globe, the laws of geologic action
through long ages of vicissitude and development, the origin of
life, the nature and source of the myriad complexities of living
beings, the advent of man, possibly even the future history of
the earth, are amongst the questions with which the geologist
has to grapple in his higher capacity.

These are problems which have occupied the attention of philosophers
in every age of the world, and in periods long antecedent to
the existence of a science of geology. The mere existence of
cosmogonies in the religion of almost every nation, both ancient
and modern, is a sufficient proof of the eager desire of the
human mind to know something of the origin of the earth on which
we tread. Every human being who has gazed on the vast panorama
of the universe, though it may have been but with the eyes of
a child, has felt the longing to solve, however imperfectly,
"the riddle of the painful earth," and has, consciously or
unconsciously, elaborated some sort of a theory as to the why and
wherefore of what he sees. Apart from the profound and perhaps
inscrutable problems which lie at the bottom of human existence,
men have in all ages invented theories to explain the common
phenomena of the material universe; and most of these theories,
however varied in their details, turn out on examination to have a
common root, and to be based on the same elements. Modern geology
has its own theories on the same subject, and it will be well to
glance for a moment at the principles underlying the old and
the new views.

It has been maintained, as a metaphysical hypothesis, that there
exists in the mind of man an inherent principle, in virtue of
which he believes and expects that what has been, will be; and
that the course of nature will be a continuous and uninterrupted
one. So far, however, from any such belief existing as a necessary
consequence of the constitution of the human mind, the real fact
seems to be that the contrary belief has been almost universally
prevalent. In all old religions, and in the philosophical systems
of almost all ancient nations, the order of the universe has
been regarded as distinctly unstable, mutable, and temporary.
A beginning and an end have always been assumed, and the course
of terrestrial events between these