NECESSITY OF LONG PERIODS. 1 29 



naturalists, make it their chief objection to these theories, 

 that they arbitrarily claim too great a length of time : yet 

 the ground of objection is scarcely intelligible. For it is 

 absolutely impossible to see what can, in any way, limit us 

 in assuming long periods of time. We have long known, 

 even from the structure of the stratified crust of the earth 

 alone, that its origin and the formation of neptunic rocks 

 from water must have taken, at least, several millions of 

 years. From a strictly philosophical point of view, it makes 

 no difference whether we hypothetically assume for this pro- 

 cess ten millions or ten thousand billions of years. Before 

 us and behind us lies eternity. If the assumption of such 

 enormous periods is opposed to the feelings of many, I regard 

 this simply as the consequence of false notions which are 

 impressed upon us from our earliest youth concerning the 

 short history of the earth, which is said to embrace only 

 a few thousands of years. Albert Lange, in his " History 

 of Materialism,"^ has convincingly^ shown that from a 

 strictly philosophical point of view it is far less objec- 

 tionable in a scientific hypothesis to assume periods which 

 are too long than periods which are too short. Every 

 process of development is the more intelligible the longer it 

 is assumed to last. A short and limited period is the most 

 improbable. 



I have no space here to enter minutely into Lyell's great 

 work, and will therefore mention only its most important 

 result, which is, that he completely refuted Cuvier's history 

 of creation with its mythical revolutions, and established in 

 its place the constant and slow transformation of the earth's 

 crust by the continued action of forces, which are still work- 

 ing on the earth's surface, viz. the movement of water and 



