ime to some preliminary considerations, in order that we may have
clearly in mind a few broad facts as to the different planes on which
clairvoyant vision may be exercised, and the conditions which render
its exercise possible.

We are constantly assured in Theosophical literature that all these
higher faculties are presently to be the heritage of mankind in
general--that the capacity of clairvoyance, for example, lies latent
in every one, and that those in whom it already manifests itself are
simply in that one particular a little in advance of the rest of us.
Now this statement is a true one, and yet it seems quite vague and
unreal to the majority of people, simply because they regard such a
faculty as something absolutely different from anything they have yet
experienced, and feel fairly confident that they themselves, at any
rate, are not within measurable distance of its development.

It may help to dispel this sense of unreality if we try to understand
that clairvoyance, like so many other things in nature, is mainly a
question of vibrations, and is in fact nothing but an extension of
powers which we are all using every day of our lives. We are living
all the while surrounded by a vast sea of mingled air and ether, the
latter inter-penetrating the former, as it does all physical matter;
and it is chiefly by means of vibrations in that vast sea of matter
that impressions reach us from the outside. This much we all know, but
it may perhaps never have occurred to many of us that the number of
these vibrations to which we are capable of responding is in reality
quite infinitesimal.

Up among the exceedingly rapid vibrations which affect the ether there
is a certain small section--a _very_ small section--to which the
retina of the human eye is capable of responding, and these particular
vibrations produce in us the sensation which we call light. That is to
say, we are capable of seeing only those objects from which light of
that particular kind can either issue or be reflected.

In exactly the same way the tympanum of the human ear is capable of
responding to a certain very small range of comparatively slow
vibrations--slow enough to affect the air which surrounds us; and so
the only sounds which we can hear are those made by objects which are
able to vibrate at some rate within that particular range.

In both cases it is a matter perfectly well known to science that
there are large numbers of vibrations both abov