consciousness are ever on the wing; they never pause
in their restless flight and we must catch them as they go. This is not
so easy as it appears; for the moment we turn to look in upon the mind,
that moment consciousness changes. The thing we meant to examine is
gone, and something else has taken its place. All that is left us then
is to view the mental object while it is still fresh in the memory, or
to catch it again when it returns.

STUDYING MENTAL STATES OF OTHERS THROUGH EXPRESSION.--Although I can
meet only my own mind face to face, I am, nevertheless, under the
necessity of judging your mental states and knowing what is taking place
in your consciousness. For in order to work successfully with you, in
order to teach you, understand you, control you or obey you, be your
friend or enemy, or associate with you in any other way, I must _know_
you. But the real you that I must know is hidden behind the physical
mask that we call the body. I must, therefore, be able to understand
your states of consciousness as they are reflected in your bodily
expressions. Your face, form, gesture, speech, the tone of voice,
laughter and tears, the poise of attention, the droop of grief, the
tenseness of anger and start of fear,--all these tell the story of the
mental state that lies behind the senses. These various expressions are
the pictures on the screen by which your mind reveals itself to others;
they are the language by which the inner self speaks to the world
without.

LEARNING TO INTERPRET EXPRESSION.--If I would understand the workings of
your mind I must therefore learn to read the language of physical
expression. I must study human nature and learn to observe others. I
must apply the information found in the texts to an interpretation of
those about me. This study of others may be _uncritical_, as in the mere
intelligent observation of those I meet; or it may be _scientific_, as
when I conduct carefully planned psychological experiments. But in
either case it consists in judging the inner states of consciousness by
their physical manifestations.

The three methods by which mind may be studied are, then: (1) text-book
_description and explanation_; (2) _introspection_ of my own conscious
processes; and (3) _observation_ of others, either uncritical or
scientific.

2. THE NATURE OF CONSCIOUSNESS

INNER NATURE OF THE MIND NOT REVEALED BY INTROSPECTION.--We are not to
be too greatly discouraged if, even by introspe