96 PROCEEDINGS OF SECTION A. 
are better suited for discussion than the record of expire 
ments or of mathematica! analysis. They afford more room 
for differences of view, and a conflict of opinion is invaluable 
in clearing and broadening our ideas.. Of course, the soiu- 
tion of a differential equation, or the structure of a soap- 
bubble, may iead to a discussion, but if it is to be of interest, 
it will generally be so because of its bearing on some larger 
idea. (2) The more general principles should be of interest 
to a wider circle. It is in the search for, or in the working 
out of these general principles, or “laws,” that most 
scientists spend cheir lives. It is well, then, that they 
should have the clearest possible views as to what these prin- 
ciples are, and discussion should conduce to clearness. 
(3) Today science is confronted with a serious danger. Its 
tendency to specialise is evidenced in a thousand ways, 
among others by the splitting up into sections and sub 
sections of associations such as this. This is doubtless neces 
sary for the advancement of science; but if specialisation be 
not kept within proper bounds, the advancement may be. 
bought too dear. The concentration of interest in smaller 
and smaller groups of facts will tend to narrow the intellect, 
and the scientist may lose his larger views and sympathies. 
This will react on the man, and make his outlook wrong. 
Thus, in the end, it will react on science. The danger is 
already quite apparent, and, if we do not take care, we may 
afford more examples of the absurd views of the world 
entertained by men that have never seen beyond a test- 
tube. I hope, then, that I need not apologise for discussing 
the scope and method of so coraprehensive a subject as 
mathematical physics. 
The first question in the catechism of a scientist should be, 
What is the chief end of science? This is.a question about 
which there is far more loose thinking, even among men of 
science, than there ought toa be; and, unfortunately, the 
looseness of thought leads into serious error when various 
great problems are being attacked. The answer that man7z 
men (perhaps most men) would give is that the end of 
science is to explain the world. | What is the scientific “ ex- 
planation” of this or that phenomenon ?—is the most common 
of questions, Now, the first point that I wish to insist on 
(of course, with all due respect to my betters) is that, if we 
use words with their ordinary meaning, sctence sens 
nothing. If we are to talk of scientific “‘ explanation,” 
must, w ve clear-heaaed, keep before our minds the ve 
that we are using this term in an unusual sense. For what 
does one mean by “explanation”? I think that there will 
