132 PROF. J. ARTHUR THOMSON. 
instinctively discount the scientific abilities of the 
student who always has his microscope wrongly focussed 
and is satisfied with the ill-defined image; or of the 
other whose dissection is invariably either mince or a 
tangle; or of the other who is never quite sure whether 
he knows a thing or not. 
Ignorance is no particular reproach; we are all 
dreadfully ignorant; the point is to know when we know 
and when we don’t. It is one of the characteristics of 
the scientific mood that it will have yes or no. “Do you 
see it or do you not?” was the continual question of one 
of the best teachers I have known. And if you see it, 
what like is it, and how is it as it is? 
A student of Agassiz’s relates how she was almost 
brought to despair by the severe way in which that 
great master, after giving her a specimen to study, came 
day after day, and asked, with a cruel kindliness, “ Well, 
what do you see now?” and then went away. But at 
length the student saw something,—saw what was to be seen. 
Those of the scientific mood are mainly trying to 
construct a working thought-model of the outer world, to 
form a mental image which will be a living picture, an 
intellectual cinematograph. In other words, they would 
make the world translucent,—as translucent as a few 
animals are to every skilled biologist. 
Can we shut our eyes and see the snail as it really is, 
see its organs each in its proper place, see its blood 
coursing, its muscles contracting, its cells waxing and 
waning, its whirlpool of living matter ?—that is part of 
the scientific picture of the snail, and yet only a part. 
Can we shut our eyes and see the tree, as a whole, 
with its wood and bast, its vessels and cells, all as they 
are, its currents of sap up and down, its ceaseless change 
from season to season ?—that is part of the scientific picture, 
of the tree, and yet only a part. 
It must not be thought, from my illustrations, that the 
scientific mood has any particular relation to biology or to 
any one order of facts. Many business men, who care 
not a whit for science in the conventional sense, have the 
scientific mood developed in great strength. 
