144 NOTES ON THE GEOLOGY OF LAKE ST. CLAIR. 
genius insisted in searching after a single basis for the expla- 
nation of all physical phenomena; their rapid progress in the 
modern age is due toa breaking up of broad problems into 
their component parts. There is no doubt an underlying 
unity in all the forces of nature, but whatever progress has 
beeu made towards discovering it has depended on knowledge 
obtained by persistent specialised study, no less than an 
occasional broad survey of the field of nature as a whole,” 
and accordingly, with Mill, he approves of another of 
Compte’s sayings, that ‘a person is not likely to be a good 
economist (might we not add also for local application, a 
good geological specialist) who is nothing else.” Although 
these observations are directed to quite a different matter, 
the central idea may yet be applied with advantage to all 
who are apt to be carried away by the fascinations of simple 
universal hypotheses of causation, as accounting for complex 
though superficially similar effects. Iam of opinion, there- 
fore, that the effort on the part of some brilliant geological 
investigators to account generally for the origin of Alpime 
Lake basins by reference to the Glacier Theory isa retrograde 
movement and a mistake. It may account for a large number 
of lake basins, but if all previous observations are not a 
blunder, it cannot account for all lakes, even in Alpine re- 
gions. Every geologist who desires to avoid imparticg error 
into his inferences from local facts of observation, must 
therefore rigidly guard against deceptive general hypotheses, 
lest they should unconsciously bias and disturb his mind 
in making correct interpretations of observed facts; and 
hence each lake basin, wherever situated, is best studied 
apart from all others on the basis of local evidences. This 
method, moreover, does not exclude the Glacier or any other 
particular agency, regarded as a cause. Apart from one’s own 
experience in support of this view, we have the best positive 
evidence of its truth in the writings of all authors of Geo- 
logical Text Books, whose imagination is kept under stricter 
control, partly by the feeling that they are more responsible 
for the teaching imparted by them, and partly by the circum- 
stance that in giving the outline ot any particular subject, 
they are led to review all the varying circumstances and con- 
ditions, and, in unsettled questions, to give the facts upon 
which they are based, in order that the student may be pro- 
perly equipped to grapple with similar difficulties when they 
appear to him. 
Sir Archibald Geikie’s luminous writings and observations 
alone suffice to overthrow the “ ONE Conprtton, OnE CAUSE” 
theory of lake origin. In his text book (p. 927) he gives a 
most true and lucid account of the various causes which are 
known to have produced lake basins, and may be briefly 
