204 WALKS AND TALKS. 



in which human caprice could have intervened. We are not 

 romancing ; we argue from cause to effect. 



This is the way reasoning leads us : Following the course 

 of cooling backward, we arrive at a time such that water could 

 not have existed on the earth. All the water of the earth 

 must have been vapor or gas suspended in the atmosphere. 

 At a time when no ocean had existed, no ocean-sediments had 

 been deposited, all those rocks which have resulted from 

 marine sedimentation were yet non-existent. The earth had 

 probably a solid surface of some kind ; but to emit heat suffi- 

 cient to hold all the water of the world in an uncondensed 

 state, the temperature of the surface must have been high 

 perhaps a glowing temperature. 



But even here we are in the midst of a cooling process. 

 Why not? Who can affirm that the world began to exist as 

 a red-hot body ? You know that red-hot matter may be made 

 white-hot; and then by increase of heat, may be rendered 

 liquid. We must trace this history back to a molten world. 



Is there now any ground for refusing to trace the history 

 farther back ? This is a cooling process. There is no certain 

 beginning for a cooling process except in a temperature so high 

 that the heated matter exists as a mere vapor, or perhaps gas. 

 There is no known remoter condition of matter, though we may 

 conceive the temperature indefinitely high. It is, let us say, 

 the remotest condition which we seek. Now all terrestrial sub- 

 stances are capable not only of fusion, but of volatilization. 

 Iron and the other metals have been reduced to vapor. So, 

 by reversing conditions, all gases may be liquefied and then 

 consolidated. Carbonic acid, oxygen, nitrogen, chlorine, 

 have been made solid. The form under which matter exists 

 is a circumstance depending on temperature and pressure. 

 There is no inherent improbability that all the matter of the 

 world was once so heated as to exist in the form of vapor, or 

 even of gas. Before our eyes worlds are existing in those 

 states. 



We should distinguish between vapor and gas. Gas is dry, 

 like atmospheric air like steam in the boiler ; vapor is com- 



