Ch. I.] 
METHODS OF THEORIZING IN GEOLOGY. 
overthrown one after the other, — which have been found quite 
incapable of modification, — and which are often required to be 
precisely reversed. 
In regard to the subjects treated of in our first two volumes, 
if systematic treatises had been written on these topics, we 
should willingly have entered at once upon the description of 
geological monuments properly so called,, referring to other 
authors for the elucidation of elementary and collateral ques- 
tions, just as we shall appeal to the best authorities in 
conch ology and comparative anatomy, in proof of many posi- 
tions which, but for the labours of naturalists devoted to 
these departments, would have demanded long digressions. 
"When we find it asserted, for example, that the bones of a 
fossil animal at (Eningen were those of man, and the fact 
adduced as a proof of the deluge, we are now able at once to 
dismiss the argument as nugatory, and to affirm the skeleton 
to be that of a reptile, on the authority of an able anatomist ; 
and when we find among ancient writers the opinion of the gigan- 
tic stature of the human race in times of old, grounded on the 
magnitude of certain fossil teeth and bones, we are able to affirm 
these remains to belong to the elephant and rhinoceros, on the 
same authority. 
But since in our attempt to solve geological problems, we 
shall be called upon to refer to the operation of aqueous and 
igneous causes, the geographical distribution of animals and 
plants, the real existence of species, their successive extinction, 
and so forth, we were under the necessity of collecting together 
a variety of facts, and of entering into long trains of reasoning, 
which could only be accomplished in preliminary treatises. 
These topics we regard as constituting the alphabet and 
grammar of geology ; not that we expect from such studies to 
obtain a key to the interpretation of all geological phenomena, 
but because they form the groundwork from which we must 
rise to the contemplation of more general questions relating to 
the complicated results to which, in an indefinite lapse of ages_, 
the existing causes of change may give rise. 
