XIV 
INTRODUCTORY OBSERVATIONS. 
of sound philosophy. If, therefore, it be absolutely 
necessary, as it unquestionably is, that, in the pur- 
suit of knowledge of any kind, before experience 
itself can be used with advantage, we must dis- 
miss from the mind all prejudices, from whatsoever 
source they may arise ; this mental purification 
becomes the more indispensable in a science like 
Geology, in which we meet, at the very threshold, 
with facts that disturb all our preconceived opi- 
nions of the nature of the globe on which we live, 
and teach us that, though man be, as it were, but 
the creature of yesterday, the earth has teemed 
with countless forms of animal and vegetable ex- 
istence, myriads of ages before the creation of the 
human race. 
Dismissing from his mind all prejudices of opi- 
nion, the geological enquirer must be prepared to 
learn, that the earth’s surface has been, and still is, 
subject to incessant fluctuation and movements ; 
and that, as the land has been the theatre of per- 
petual mutation, the sea can alone be considered 
as having undergone no change ; the apostrophe 
of the noble bard to the ocean is therefore as phi- 
losophical, as it is highly poetical and sublime : — 
“ Unchangeable, save to thy wild waves’ play. 
Time writes no wrinkle on thine azure brow — 
Such as creation’s dawn beheld, thou rollest now!” 
Byron. 
To render this volume more intelligible to the 
general reader, we shall offer a brief notice of the 
leading princijilcs of modern geology ; referring, 
for further information on this sublime and im- 
