580 HISTOEY OF GEOLOGY. 



ble that their labors would have been far less zealous, and then 

 expositions far less impressive. We by no means regret, therefore, 

 the mixture of these two kinds of knowledge, which has so often 

 occurred ; but still, it is our business to separate them. The works of 

 astronomers before the rise of sound physical astronomy, were full of 

 theories, but these were advantageous, not prejudicial, to the progress* 

 of the science. 



Geological theories have been abundant and various ; but yet oui 

 history of them must be brief. For our object is, as must be borne in 

 mind, to exhibit these, only so far as they are steps discoverably tend- 

 ing to the true theory of the earth : and in most of them we dc 

 not trace this character. Or rather, the portions of the labors of 

 geologists which do merit this praise, belong to the two preceding 

 divisions of the subject, and have been treated of there. 



The history of Physical Geology, considered as the advance towards a 

 science as real and stable as those which we have already treated of (and 

 this is the form in which we ought to trace it), hitherto consists of few 

 steps. We hardly know whether the progress is begun. The history 

 of Physical Astronomy almost commences with Newton, and few per- 

 sons will venture to assert that the Newton of Geology has yet appeared. 



Still, some examination of the attempts which have been made is 

 requisite, in order to explain and justify the view which the analogy 

 of scientific history leads us to take, of the state of the subject. 

 Though far from intending to give even a sketch of all past geological 

 speculations, I must notice some of the forms such speculations have 

 at different times assumed. 



Sect. 2. Of fanciful Geological Ojiinions. 



REAL and permanent geological knowledge, like all other physical 

 knowledge, can be obtained only by inductions of classification and 

 law from many clearly seen phenomena. The labor of the most 

 active, the talent of the most intelligent, are requisite for such a pur- 

 pose. But far less than this is sufficient to put in busy operation the 

 inventive and capricious fancy. A few appearances hastily seen, and 

 arbitrarily interpreted, are enough to give rise to a wondrous tale of 

 the past, full of strange events and supernatural agencies. The mytho- 

 logy and early poetry of nations afford sufficient evidence of man's 

 love of the wonderful, and of his inventive powers, in early stages of 

 intellectual development. The scientific faculty, on the other hand. 



