36 PRESIDENT’S ADDRESS—SECTION A. 
upon something higher than the phenomena on which the con- 
ceptions and relations operate (6). Thus, in proposing to reach 
an intelligible and consistent view of all natural phenomena, we 
are brought face to face with questions of criteria of intelligi- 
bility and consistency; that is to say, with problems of pure 
metaphysic. 
34. The Problem Simplified through Ideal Analogres.— 
If in the attempt to reduce phenomena under general concep- 
tions, their classification into groups, for the purpose of syste 
matic study, had revealed that each, with respect to the rest, was 
sur generis, so that the establishment of a scheme of hypo- 
thetical relations between the members of one group, was with- 
out applicability to those of the others, the difficulty of 
interpretation would probably have been felt as overwhelming. 
Fortunately, however, experience has shown that between 
apparently very different orders of facts there are analogies of so 
general and all-inclusive a character that the conceptions 
applicable to the one may be transferred to the other. Thus, 
for example, the theory of inertia and of motion enable us to 
predict the character of the flight of a projectile, or, with some 
limitation, to deduce from their chemical composition the boil- 
ing points of liquids, or the melting points of solids. Or an 
illustration of broader significance would be the wide application 
of certain forms of mathematical solution, those, for example, 
one meets in hydrokinetics (c). 
35. The Causal Nexus Assumed.—A consideration of the 
processes by which phznomena are reduced under general con- 
ceptions will show that they are presumed to be so linked 
together that one is conceived as dependent upon the other. 
That is to say, we universally assume the causal relation. For 
the general purposes merely of natural science, it is, perhaps, 
practically immaterial what theory we entertain in respect of 
causation, 7.¢., whether we regard it as a fiction of the intellect, 
a mode in which we are compelled to think, if we think at all, 
pr as something the validity of which is at least confirmed by the 
general trend of human experience. 
36. The Nexus Conceived as Actually or Potentially Phe- 
nomenal.—Whatever our view, it is easy to see that the nexus 
between phznomena is and must finally be essentially ideal, 
since it is not given in perception. Itis really postulated by the 
intellect in virtue of an original tendency in our nature, viz., 
(v) The admission of the doctrine attributed to Aristotle, ‘‘ nihil in intellectu, quod non 
prius fuerit in sensu,” to which, by the way, Leibnitz, in his polemic against Locke, added 
*‘ nisi ipse intellectus,’’ is by no means hopelessly inconsistent with this dictum, for that on 
which the intellect operates may always be taken as coming through the channel of sense- 
experience. 
&) The striking correlation of several mathematical theories was the theme of the 
interesting address by Prof. Bragg to this section in 1892. A.A.A, Sc. Hobart. Pp. 
31-47. 
