so that the force which comes through them
and is the cause of their existence seems to well up from nowhere. But
at any rate, since all particles in turn pass through each of them, it
will be clear that it is thus possible for each in turn to evoke in
all the particles of the body the power of receptivity to a certain
set of vibrations, so that all the astral senses are equally active in
all parts of the body.

The vision of the mental plane is again totally different, for in this
case we can no longer speak of separate senses such as sight and
hearing, but rather have to postulate one general sense which responds
so fully to the vibrations reaching it that when any object comes
within its cognition it at once comprehends it fully, and as it were
sees it, hears it, feels it, and knows all there is to know about it
by the one instantaneous operation. Yet even this wonderful faculty
differs in degree only and not in kind from those which are at our
command at the present time; on the mental plane, just as on the
physical, impressions are still conveyed by means of vibrations
travelling from the object seen to the seer.

On the buddhic plane we meet for the first time with a quite new
faculty having nothing in common with those of which we have spoken,
for there a man cognizes any object by an entirely different method,
in which external vibrations play no part. The object becomes part of
himself, and he studies it from the inside instead of from the
outside. But with _this_ power ordinary clairvoyance has nothing to
do.

The development, either entire or partial, of any one of these
faculties would come under our definition of clairvoyance--the power
to see what is hidden from ordinary physical sight. But these
faculties may be developed in various ways, and it will be well to say
a few words as to these different lines.

We may presume that if it were possible for a man to be isolated
during his evolution from all but the gentlest outside influences, and
to unfold from the beginning in perfectly regular and normal fashion,
he would probably develop his senses in regular order also. He would
find his physical senses gradually extending their scope until they
responded to all the physical vibrations, of etheric as well as of
denser matter; then in orderly sequence would come sensibility to the
coarser part of the astral plane, and presently the finer part also
would be included, until in due course the faculty of th