tance, by means of a process loosely referred to as
"differentiation," all the elements are derived. These elements are
the result of atomic arrangement, and the atoms of each are known
to have various vibrations, the extent of which is called the "mean
free path of vibration." The indestructibility of matter, the fact that
all nature is convertible, and the absolute association of matter and
force, lead to the conclusion that since every change in matter
implies a change of force, matter must be ever living and active,
and primarily of a spiritual nature. The great Swedenborg, no less
a scientist than a spiritual seer, laid down his doctrine of
"Correspondences" upon the primary concept of the spiritual
origin of all force and matter. Matter, he argued, was the ultimate
expression of Spirit, as Form was that of Force. Spirit was to Force
what Matter was to Form--our ideas of Matter and Form being
closely related. Hence, for every _Spiritual Force_ there is a
corresponding _Material Form_, and the material or natural world
corresponds at all points with the world of spirit, without being
identical. This, in brief, is the conclusion to which the "scientific
imagination" of the present day, extending as it does from the
known into the unknown, is slowly but surely leading up.

Taking as our postulate the scientific statement of the atomic
structure of bodies, atomic vibration and molecular arrangement,
we turn to consider the action exerted by such bodies upon the
nervous organism of man.

The function of the brain--which must be regarded as the bulbous
root of a nervous plant whose branches grow downwards--is
twofold; to affect, and to be affected. In its active or positive
condition it affects the whole of the vital and muscular processes
in the man, finding expression in vital action. In its passive or
negative state it is affected by impressions coming to it in different
ways through the sense-organs, resulting in nervous and mental
action. It is this latter phase of brain-function with which we are
immediately concerned.

The range of our sense-perception puts us momentarily and
continually in relation with the material world, or rather with a
_certain portion_ of it. We say a certain portion because we
know from scientific experience that the scale or gamut of
sense-perception is limited, both as to its extent and as to its
quality. Many insects, birds, and quadrupeds have keener perceptions
in some respects th