1 82 EVOLUTION OF THE EARTH 



Contribution of tropical countries. In these later days since 

 historical records have been kept, the contribution of tropical 

 countries to civilization has been as meager as appears to have 

 been the case in the remote past. So far as we are aware, no 

 truly prpat- mijp p-Ypppfr Mohammed hasj^rjfrfrn w^hi" twenty- 

 five degrees of the equator. Gautama, the founder of Bud- 

 dhism, lived north of this limit. Moreover, his home was 

 among the mountains where the climate is more stimulating 

 than in the lowlands. Mesopotamia had its great men whose 

 names are still known, but that country, though hot in summer, 

 lies from thirty to thirty-five degrees north of the equator. So 

 too with Egypt, for its great men almost without exception 

 lived from Thebes northward, and the latitude of Thebes is 

 more than twenty-five degrees north. In modern times it is 

 even harder than in the past to find great men who lived in 

 tropical or even in warm countries. Diaz in the high, cool, 

 but nevertheless tropical plateau of Mexico may be cited as an 

 example, but a hundred years from now only the special stu- 

 dent will have heard of him, while men like Lincoln, Pasteur, 

 and Humboldt will still be admired by thousands, yea, millions 

 of people. Even if we go back to Mohammed as an example 

 of a truly great man arising within the tropics, we find that 

 his ideas came to fruition only when they were carried north- 

 ward to a place where the minds of that generation were more 

 alert than in southern Arabia. 



We have now seen that civilization is today highest in places 

 where climatic energy is also high. We have likewise seen that 

 in the past no great steps in human progress seem to have been 

 taken in tropical countries, nor do great men appear to have 

 sprung up there in appreciable numbers. These considerations 



I apparently lead to the conclusion that when the progress of 

 11 human civilization is viewed in the broadest light its great 



II movements depend upon climate almost as closely as do the 

 n pulsations of the evolutionary stream in geological times. One 



