of expression, actually summon to your assistance added powers of mind.  For example, when you are called upon to recite in class, your mind seems to be a complete blank—­in a state of “deadlock.”  You may break this “deadlock” and start brain-action by some kind of movement.  It may be only to clear your throat, to ejaculate “well,” or to squirm about in the seat, but whatever form the movement takes, it will usually be effective in creating the desired nervous energy, and after the inertia is once overcome the mental stream will flow freely.  The unconscious application of this device is seen when a man is called on suddenly to make a speech for which he has not prepared.  He usually starts out by telling a story, thus liberating nervous energy to pour back into the brain and start thinking processes.  With increasing vehemence of expression, the ideas come more and more freely, and the result is a speech which surpasses the expectations of the speaker himself.  The gesticulations of many speakers have this same function, being frequently of great service in arousing more nervous energy, which goes back to the brain and arouses more ideas.

The device of stimulating ideas by expressive movements may be utilized in theme- or letter-writing.  It is generally recognized that the difficult thing in such writing is to get a start, and the too common practice is to sit listlessly gazing into space waiting for “inspiration.”  This is usually a futile procedure.  The better way is to begin to write anything about the topic in hand.  What you write may have little merit, either of substance or form.  Nevertheless, if you persist in keeping up the activity of writing, making more and more movements, you will find that the ideas will begin to come in greater profusion until they come so fast you can hardly write them down.

Having tried to picture the neural effect of expression, we may now translate them into psychological terms, asking what service the expressions render to the conscious side of our study.  First of all, we note that the expressions help to make the acts and ideas in study habitual.  We find ourselves, with each expression, better able to perform such acts as the pronunciation of foreign words.  Second, they furnish new impressions through the kinaesthetic sense, thus being a source of sense-impression.  Third, they give rise to a greater number of ideas and link them up with the idea dominant at the moment.  There is a further psychological effect of expression in the clarification of ideas.  It is a well-attested fact that when we attempt to explain a thing to someone else, it becomes clearer in our own minds.  You can demonstrate this for yourself by attempting to explain to someone an intricate conception such as the nebular hypothesis.  The effort involved in making the explanation makes the fact more vivid to you.  The habit of thus utilizing your knowledge in conversation is an excellent one to acquire.  Indeed, expression is the only objective test of knowledge