l that can be ascertained concerning the structure, succession of
conditions, actions, and position in space of the earth, is the matter of
fact of its natural history. But, as in biology, there remains the matter
of reasoning from these facts to their causes, which is just as much
science as the other, and indeed more; and this constitutes geological
aetiology.

Having regard to this general scheme of geological knowledge and thought,
it is obvious that geological speculation may be, so to speak, anatomical
and developmental speculation, so far as it relates to points of
stratigraphical arrangement which are out of reach of direct observation;
or, it may be physiological speculation so far as it relates to
undetermined problems relative to the activities of the earth; or, it may
be distributional speculation, if it deals with modifications of the
earth's place in space; or, finally, it will be aetiological speculation
if it attempts to deduce the history of the world, as a whole, from the
known properties of the matter of the earth, in the conditions in which
the earth has been placed.

For the purposes of the present discourse I may take this last to be what
is meant by "geological speculation."

Now Uniformitarianism, as we have seen, tends to ignore geological
speculation in this sense altogether.

The one point the catastrophists and the uniformitarians agreed upon,
when this Society was founded, was to ignore it. And you will find, if
you look back into our records, that our revered fathers in geology
plumed themselves a good deal upon the practical sense and wisdom of this
proceeding. As a temporary measure, I do not presume to challenge its
wisdom; but in all organised bodies temporary changes are apt to produce
permanent effects; and as time has slipped by, altering all the
conditions which may have made such mortification of the scientific flesh
desirable, I think the effect of the stream of cold water which has
steadily flowed over geological speculation within these walls has been
of doubtful beneficence.

The sort of geological speculation to which I am now referring
(geological aetiology, in short) was created, as a science, by that famous
philosopher Immanuel Kant, when, in 1775, he wrote his "General Natural
History and Theory of the Celestial Bodies; or an Attempt to account for
the Constitutional and the Mechanical Origin of the Universe upon
Newtonian principles."[11]

[Footnote 11: Grant (_His