336 THE JOURNAL OF GEOLOGY. 
it.’ The remark reminds one much of the answer given by 
Lincoln to a question as to how he gained so clear a knowl- 
edge of the subjects with which he dealt, when he said: “I 
cannot rest easy when I am handling a thought till I have 
bounded it upon the north, upon the south, upon the east and 
upon the west.” 
Another maxim which it would be well to keep in mind in 
these days of easy publication Professor Dana gave utterance to 
when, in referring to some of the theories which were being 
advanced at the time to account for the subsidences of the earth’s 
crust, he said: ‘I think it better to doubt until you know. Too 
many people assert and then let others doubt.” 
The same judicial poise was exhibited in his readiness to 
change his former opinions when he became convinced that the 
evidence was sufficient to warrant it. Absolute candor and desire 
to support only the trith as he saw the truth were among his. 
principal characteristics, and he sought constantly to impress 
upon his students their importance as factors of success in the 
pursuit of knowledge. 
Thus in studying the Cambrian era, which the labors of Wal- 
cott and others at that time had shown to be of far greater extent 
and importance than had previously been supposed, his students 
were told to regard it as of equal importance with the Lower 
Silurian, though in his text-book it was one of the subdivisions 
of the latter, and his remark at the time was: ‘‘I have found it 
best to be always afloat in regard to opinions on geology.” 
So too in accepting as divisions of independent continental 
progress, the Eastern Border, Eastern Continental, Interior Con- 
tinental, Western Continental and Western Border regions, a 
classification which differed from that which he had previously 
made, he said: ‘I always like to change when I can make a 
change for the better.” 
In adopting views which had been originated by others, he 
never sought to assume from them any credit to himself, but 
freely gave honor to whom honor was due. This was well illus- 
trated in his espousal of Darwin’s theory of the formation of 
