49 PRESIDENTS ADDRESS — SECTION A. 
disposed to excuse conduct in an atom that we will not tolerate 
in a bigger creature. If action at a distance be really not im- 
plied, then the conception itself has elements equally defying all 
understanding. 
Is not the fact simply this, that in so-called mechanical inter- 
pretations we have deliberately elected to regard motion as pos- 
sible only through actual contact ; we have arbitrarily decided 
that no other conception is to be treated as intelligible or pic- 
turable. That is to say, we construct our explanations of Nature 
in terms of one of the lowest elements in our experience, vizZ., 
the tactual sense, and sense of muscular effort. And unless we 
introduce purely fictitious, supersensible, and mexplicable 
entities, we find that after getting rid of our bogey, it has re- 
appeared undismayed. 
Arbitrary Character of Mechanical Interpretation of Nature. 
—Moreover, is not the fact that the phenomena of Nature can- 
not be reduced under the mechanical conception adequate evi- 
dence of its purely conventional and purely arbitrary character ? 
And are we not, therefore, justified while this is so, in distinguish- 
ing between Reality and that Conceptual World which we fabri- 
cate to represent certain of its elements? A point, a curve, a 
surface, and a volume are conceptual entities dealt with by the 
mathematician, and between which he discovers, in the recesses 
of consciousness, not in external Nature, a multitude of relations, 
some of extraordinary beauty and complexity. Out of these 
entities he creates ideal forms and structures, which, projected on 
to the world of phznomena, or, if you will, the real world, serve 
to represent its geometrical features. The straight lines, curves, 
surfaces of various orders, and solid forms of the mathematician 
may, as it were, be said to have no real existence; in }magina- 
tion, however, he projects them on, or applies them, to the forms 
in Nature, and when for the purpose immediately in view, or by 
reason of our limitations in discrimination, the two are 
apparently identical, the conceptual elements may be said to 
represent the real. The actual forms in Nature are probably so 
complex as to completely baffle any attempt at absolute geo- 
metrical representation. Nevertheless, we apply the elementary 
and, relatively, meagre concepts of geometry as the only pos- 
sible way of rendering them intelligible. We say, for example, 
that sodium chloride crystallises in the form of a cube, that the 
angle between contiguous faces is 90 deg. But in reality the 
angle varies about a-half degree either way. We describe a leaf 
as, say, ovate, or sagittate, or of some other form implying 
symmetry ; in reality leaves are asymmetrical. We affirm that 
a planet moves round the sun in an ellipse; in reality the path 
is bewilderingly complex. Thus we see that our conceptions are 
fictions, by which reality is represented ; and this 1s no less true 
in the domain of physies. 
