agencies, either out of the waste and washing of the dry
land, or else by the accumulation of the exuviae of plants and animals.
Many of these strata are full of such exuviae--the so-called
"fossils."

Remains of thousands of species of animals and plants, as perfectly
recognizable as those of existing forms of life which you meet with in
museums, or as the shells which you pick up upon the seabeach, have been
embedded in the ancient sands, or muds, or limestones, just as they are
being embedded now, in sandy, or clayey, or calcareous subaqueous
deposits. They furnish us with a record, the general nature of which
cannot be misinterpreted, of the kinds of things that have lived upon
thy surface of the earth during the time that is registered by this
great thickness of stratified rocks. But even a superficial study of
these fossils shows us that the animals and plants which live at the
present time have had only a temporary duration; for the remains of such
modern forms of life are met with, for the most part, only in
the uppermost or latest tertiaries, and their number rapidly diminishes
in the lower deposits of that epoch. In the older tertiaries, the places
of existing animals and plants are taken by other forms, as numerous and
diversified as those which live now in the same localities, but more or
less different from them; in the Mesozoic rocks, these are replaced by
others yet more divergent from modern types; and in the Paleozoic
formations the contrast is still more marked. Thus the circumstantial
evidence absolutely negatives the conception of the eternity of the
present condition of things. We can say with certainly that the present
condition of things has existed for a comparatively short period; and
that, so far as animal and vegetable nature are concerned, it has been
preceded by a different condition. We can pursue this evidence until we
reach the lowest of the stratified rocks, in which we lose the
indications of life altogether. The hypothesis of the eternity of the
present state of nature may therefore be put out of court.

We now come to what I will term Milton's hypothesis--the hypothesis that
the present condition of things has endured for a comparatively short
time; and, at the commencement of that time, came into existence within
the course of six days. I doubt not that it may have excited some
surprise in your minds that I should have spoken of this as Milton's
hypothesis, rather than that I should