130 PROF. J. ARTHUR THOMSON. 
so unwilling to commit themselves unless they are sure. 
It may even be that the excessive changeableness of Scotch 
weather has helped to engender the scientific mood of 
caution. Sometimes, indeed, this cautiousness becomes a 
disease. I have heard three saving clauses in a single 
sentence, and however we may differ as to the precise date 
of its end it seems unnecessarily careful to speak of the so- 
called 19th century. 
No doubt the scientific mood must make hypotheses 
or guesses at truth; the scientific use of the imagination 
is part of our method. But what we have to guard 
against is the insidious tendency to mistake provisional 
hypotheses for full-grown theories, and, still worse, for 
dogmas. As Mr Bateson has phrased it, we wish to 
avoid “giving to the ignorant as a gospel, in the name of 
science, the rough guesses of yesterday that to-morrow 
should forget.” 
As Prof. W. K. Brooks says in his interesting book 
entitled The Foundations of Zoology—“The hardest of 
intellectual virtues is philosophic doubt, and the mental 
vice to which we are most prone is our tendency to believe 
that lack of evidence for an opinion is a reason for 
believing something else.” ... “Suspended judgment is 
the greatest triumph of intellectual discipline.” As Huxley 
said—and who has had the scientific mood more strongly 
developed—“ The assertion that outstrips the evidence is 
not only a blunder but a crime.” 
The point is this:—just as burnt bairns dread the fire, 
so the scientific mood, often deceived by hearsay evidence, 
by incomplete induction, by the will-o-the-wisp glamour 
of a fetching idea, by inference mixed up with observation, 
and even by wilful falsehood, becomes more and more 
cautious, distrustful, canny. 
Perhaps you may think that I exaggerate the need for 
caution, but it is not so. I take, for instance, from the 
Daily Chronicle not very long ago, this cutting, to read 
which may not be a waste of time :— 
“A Monster MeEreorite.—A valuable addition to the 
treasures of the Meteorological Section of the British 
Museum is on the way from Australia. This is what is 
