Traijiiiig of a Geologist. — I'aii Hisc. 169 
occurred in all ages,' '•' the statements show the author to be so 
lacking" in a comprehension of the principles of physics that 
he is unable to estimate whether or not a phenomenon of physics 
is likely or not likely to be true. It is clear that a man may be 
an authority as to biology, and yet be so ignorant of the rules 
of physics that he mav be as simple as a child in refer^i^ce to 
that subject. I'pon the-©^h^r~hand, a man who has a firm un- 
derstandit>g;.^j&l--ttfe principles applicable to a -case, or, in other 
words, linows the rukis of thp garrre, is likely to be al)le to 
reach a rather definite conclusion as to whether or not an ex- 
planatioa which suggested itself is in accordance with those 
rules, and therefore may be true, or disagrees with some of 
the well established rules, and therefci.; is not worth consider- 
ing. 
A geologist once said to me of my teacher and early geolog- 
ical guide, professor Irving, that he was more correct as to the 
structure of the l^ake Superior region than he ought to have 
been. But I say that every man is just a? correct as to de- 
duction beyond observed facts as he should be. Men with 
defective basal training and poor intellectual power will al- 
ways fail when they try to put facts together under principles, 
and especially wdien they attempt to project by deduction be- 
}-ond observed facts. But men who have a firm grasp of th(? 
principles of the sciences basal to geology, the capacity to 
correlate these principles, and apply them to the facts of geolo- 
gy, will go beyond their observations and by deduction will 
reach conclusions with perfect confidence which are far in 
advance of observation. Indeed in this way only can the best 
geological work be done. After one has projected his deduc- 
tions in advance of obser^'ations, he returns to the field witli 
these new ideas, and then carries his observaticns further than 
he' was able to do before. The geologist whose ideas are not 
continually outrunning his observations will never go far 
in the science. He whose mind is behind his observations in- 
stead of in advance of them, will ever be mediocre. The 
minds of the leaders of geologv are on the nountain bights 
before their feet have more than touched the foothills. 
The conclusions deduced by a sci:'ntific genius may g^o so 
far in advance of observations that he who announces the con- 
*'"The Won lerful Cfiitury," t)y .Ai.i-kkd Ktsshi.i. Wai.lace, p. 211. 
