essages and to answer them.

During any five minutes of a walk down a city street a man has
hundreds of visual images flashed upon the retina of the eye. His eye
sees every little line in the faces of the passers-by, every detail of
their clothing, the decorations on the buildings, the street signs
overhead, the articles in the shop-windows, the paving of the
sidewalks, the curbings and tracks which he crosses, and scores of
other objects to most of which the man himself is oblivious. His ear
hears every sound within hearing distance,--the honk of every horn,
the clang of every bell, the voices of the people and the shuffle of
feet. Some part of his mind feels the press of his foot on the
pavement, the rubbing of his heel on his stocking, the touch of his
clothing all over his body, and all those so-called kinesthetic
sensations,--sensations of motion and balance which keep him in
equilibrium and on the move, to say nothing of the never-ending stream
of messages from every cell of every muscle and tissue of his body.

Out of this constant rush of stimuli our man gives attention to only
the smallest fraction. Whatever is interesting to him, that he sees
and hears and feels. All other sensations he passes by as indifferent.
Unless they come with extraordinary intensity, they do not get over
into his consciousness at all.

="Listening-in" on the Subconscious.= The subconscious mind knows and
needs to know what is happening in the farthermost cell of the body.
It needs to know at any moment where the knees are, and the feet;
otherwise the individual would fall in a heap whenever he forgot to
watch his step. It needs to know just how much light is entering the
eye, and how much blood is in the stomach. To this end it has a system
of communication from every point in the body and this system is in
constant operation. Its messages never cease. But these messages were
never meant to be in the focus of attention. They are meant only for
the subconscious mind and are generally so low-toned as to be easily
ignored unless one falls into the habit of listening for them. Unless
they are invested with a significance which does not belong to them,
they will not emerge into consciousness as real sensations.

=Psychic Thresholds.= Boris Sidis has given us a word which has proved
very useful in this connection. The limit of sensitivity of a
cell--the degree of irritability--he calls the stimulus-threshold.[59]
As the wind must come in