THE HUMAN SPECIES. 377 



medium of disjointed texts of ancient writers, far re- 

 moved from the localities, but where they first began ; 

 for, in order to form a fair estimate of realities, it 

 is important to study the local geography, and to 

 become thoroughly conversant with the science of 

 what is technically denominated reading the ground ; 

 that is, of grasping the conditions of every topogra- 

 phical and geographical fact ; of appreciating the con- 

 sequences attendant on residing or migrating across, 

 up or down, the current of streams ; of toiling through 

 snow-clad regions, turning a long range, or finding an 

 approach to mountain passes, through marshes and 

 forests, straits by sea, and straits on land ; of migra- 

 tions to be accomplished, not by hunters, but by 

 tribes, who have their families and property to carry 

 with them, and must be able to find food in their pro- 

 gress. In opening thus the book of nature, and learn- 

 ing how realities should be dealt with, there remain 

 many other considerations to be kept in view, such as 

 climate and seasons, periods of frost, of ice, or of 

 drought and monsoon winds. Still more, in order to 

 trace the march of ancient nations, it is requisite to 

 search for marks attesting man's handywork, in evi- 

 dence of his passage ; for troglodyte habitations, sepul- 

 chral ruins, and piles of stones, tell also, and more 

 forcibly, of bygone ages, than texts of mere individual 

 authority ; nay, they often disprove them, and invali- 

 date remote chronology. In proportion as we may 

 interpret rightly these documents of nature and time, 

 we shall understand human doings in the infancy of 



