6 PRIN'CIPLES OF PALEONTOLOGY. 



the world is truly in its " hoary eld," and that its present stale 

 is really the result of the tranquil and regulated action of 

 known forces through unnumbered and innumerable centuries. 



The most important point for us, in the present connection, 

 is the bearing of these opposing doctrines upon the question 

 as to the origin of the existing terrestrial order. On any doc- 

 trine of uniformity that order has been evolved slowly, and, 

 according to law, from a pre-existing order. Any doctrine of 

 catastrophism, on the other hand, carries with it, by implica- 

 tion, the belief that the present order of things was brought 

 about suddenly and irrespective of any pre-existent order ; and 

 it is important to hold clear ideas as to which of these beliefs 

 is the true one. In the first place, we may postulate that the 

 world had a beginning, and, equally, that the existing terrestrial 

 order had a beginning. However far back we may go, geology 

 does not, and cannot, reach the actual beginning of the world ; 

 and we are, therefore, left simply to our own speculations on 

 this point. With regard, however, to the existing terrestrial 

 order, a great deal can be discovered, and to do so is one of 

 the principal tasks of geological science. The first steps in the 

 production of that order lie buried in the profound and un- 

 searchable depths of a past so prolonged as to present itself to 

 our finite minds as almost an eternity. The last steps are in 

 the prophetic future, and can be but dimly guessed at. Be- 

 tween the remote past and the distant future, we have, however, 

 a long period which is fairly open to inspection ; and in saying 

 a "long" period, it is to be borne in mind that this term is 

 used in its geological sense. Within this period, enormously 

 long as it is when measured by human standards, we can trace 

 with reasonable certainty the progressive march of events, and 

 can determine the laws of geological action, by which the pre- 

 sent order of things has been brought about. 



The natural belief on this subject doubtless is, that the 

 world, such as we now see it, possessed its present form and 

 configuration from the beginning. Nothing can be more 

 natural than the belief that the present continents and oceans 

 have always been where they are now; that we have always 

 had the same mountains and plains ; that our rivers have 

 always had their present courses, and our lakes their present 

 positions ; that our climate has always been the same ; and 

 that our animals and plants have always been identical with 

 those now familiar to us. Nothing could be more natural 

 than such a belief, and nothing could be further removed from 

 the actual truth. On the contrary, a very slight acquaintance 

 with geology shows us, in the words of Sir John Herschel, that 



