210 PHYSICAL BASIS OF CIVILIZATION 



etc. The depth and pressure tension of the atmos- 

 phere must therefore have been incomparably much 

 greater at that time than it is found now. Beyond 

 this it is hardly worth while to speculate until pres- 

 ent knowledge has been largely expanded along 

 this line. 



The earth's atmosphere must obviously have 

 passed through all intermediate grades of tempera- 

 ture, pressure, and kinetic energy of chemical affin- 

 ities during the period in which it was gradually 

 falling from the greater intensities which existed 

 before life, to those which have prevailed since then. 

 Within this series of intermediate degrees there 

 must obviously have occurred one, at least, which 

 was the very one in which temperature, pressure, 

 and kinetic activity of chemical affinities provided 

 the exact equivalents of the presence of living organ- 

 isms in the formation of protoplasmic compounds, 

 and by which the same results could therefore be 

 accomplished. Otherwise there could not now be, 

 or ever have been, any life on earth. This is about 

 as near as knowledge can at present come to the 

 place, time, and conditions where and when non- 

 living matter first passed into living. 



While the above leaves much uncertainty with 

 reference to many important factors in the prob- 

 lems of the beginning of life, it settles one point, 

 viz., that the quantity of protoplasmic compounds 

 (life substance) formed in the earliest period 

 depended entirely on the amount of suitable material 



