The Past and Present Aspects of Geology. 3 
force themselves upon us at every step, and even influence our 
classification and nomenclature.’ The particular theory, of a general 
nature, which then occupied the minds of Geologists was that of the 
Uniformity of Geological Causes, commonly called the ‘Doctrine of 
Uniformity ; and, although there must have been a beginning when 
the causes in operation were different in degree (if not in kind) from 
those now in action, yet we may consider the doctrine to be probably 
true for that portion of time represented by the stratified and meta- 
morphic rocks (being, indeed, all with which Geology has properly 
to deal) ; thus we may legitimately add the Idea of Uniformity (which 
we owe to Hutton and Sir Charles Lyell) to those other ideas to 
which we have already alluded. 
We now come to the present epoch in the History of the Science. 
It will be seen that during the first stages of that history Geologists 
had mainly but one or two great objects in view; but in what we 
have termed the Second Classificatory Stage, although we have cited 
but one great event as characteristic of the period, yet at the same 
time many men occupied themselves in ascertaining the causes of 
local phenomena. Such theories as they put forth are perfectly 
legitimate ; and such theorists have increased in number and impor- 
tance during the present period. Nevertheless our Science is 
eclectic, and has been so since the formation of the Geological 
Society. One of the greatest benefits to the Science produced by 
that event was, indeed, the impression of this eclectic character upon 
legitimate geological investigation. Prior to the formation of that 
body every hypothesis, however crude and wild, was considered 
legitimate, because there was no code of philosophical laws by which 
it could be tried ; but the uncompromising exclusion of hypothetical 
memoirs from the publications and meetings of the Society was the 
means of causing a broad sharp line of demarcation to be drawn 
between the legitimate and the unphilosophical. 
The establishment of the Idea of Uniformity wrought, however, 
another change, as it enlarged the field of geological research. 
Through it theories were considered legitimate that did not require 
other causes than those seen now in action ; but there has long been 
a tendency to encroach even upon this widened boundary. ‘This is 
only what could have been predicted ; for, in proportion as our 
knowledge increases, so does our ability to theorize. It is now 
rightly considered legitimate to call in the agency of forces which, 
though not seen in operation in nature, may be evoked in the labora- 
tory; and we thus seem to be in a fair way of obtaining an insight 
into the causes of some of the most obscure physical phenomena. 
These attempts to enlarge the legitimate field of geological investi- 
gation may, therefore, be considered to have been attended with 
results beneficial to the Science ; and instead of the single line of 
research of a century ago, we have now a perfect labyrinth, each 
path being an avenue of thought paved with its fundamental ideas, 
and supported and lined by the facts that have been accumulated by 
Geologists during the last fifty years. 
The present epoch in the history of Geology may also be said to be 
B 2 
