FIFTH LECTURE. 



EXPLANATIONS, OR HOW PHENOMENA ARE 



INTERPRETED. 



BY A. E. DOLBEAR. 

 (Tufts College, College Hill, Mass.) 



How long a time mankind has been on the earth no one 

 knows. When I was a lad I was taught that the earth was 

 made about six thousand years ago. Archbishop Usher's 

 chronology was accepted by all except a few geologists, and 

 their conclusions were considered as speculative vagaries, in- 

 vented by men whose object was to bring the Bible into dis- 

 repute, and against whom it was the duty of men who loved 

 the truth and who believed they possessed it to warn the young. 

 Now it is believed that the great pyramid of Gizeh has been 

 standing for nearly, if not quite as long a time, and Egypt was 

 a thickly settled country with well-established government, 

 laws, customs, religion which had then existed for a long time. 

 Back of Egypt was Assyria and other peoples, and farther back 

 still other peoples, and so on till all was lost in an antiquity 

 reaching back probably fifty thousand years and perhaps twice 

 that period. What has brought about the change in opinion 

 as to a matter of that character which cannot be rigorously 

 demonstrated, and why has any one more than a speculative 

 interest in it ? The answer to the first is that new data have 

 been found bearing upon the question which our ancestors did 

 not have, and a necessity was felt for making every kind of testi- 

 mony logically consistent with every other kind. To the 

 second, one must say that every thoughtful person who is 

 interested in his own existence and humanity has hopes and 

 fears ; he is aware without reasoning upon it that a knowledge 



