[Sidenote:  Slow Muscles Slow Mind]

There is abundant scientific proof that the quality and quantity of muscle, brain, and nerve (physical) activity in a particular individual are accompanied by corresponding qualities and quantities of mental activity.  That is, when a person’s muscle action, nerve response, and brain action are sluggish, his mind also develops a characteristic of slow action.  And vice versa.

We say of a certain acquaintance that he has an alert mind.  But his “ego,” or mental self, could not act quickly and alertly if his brain, the physical instrument of his mind, did not receive and transmit impressions swiftly to his mentality.  The brain does not think.  It is as purely physical as any other part of the body.  It just handles, or transmits in and out, to and from the mind, the various impressions sent in by different sense muscles, and the mental reflexes or impulses sent out by the innumerable mind centers.  Your mind works through your brain.  Of course, therefore, the quality and quantity of mental work you are capable of doing are limited by the degree of handling-or-transmitting efficiency characteristic of your particular brain structure.

[Sidenote:  Value of Practical Psychology]

Any interference with the brain quality or quantity of an individual naturally interferes with his normal mental functioning.  If a particular part of a man’s brain is injured, the associated mind center is harmed likewise and his mental quality is affected in proportion.  Should a certain portion of his brain be cut out, the total quantity of his mental powers would be correspondingly reduced.  We all know these things about the brain and the mind.  But only a few scientists are familiar with many details of the inter-relation of mind and brain and muscles, which should be known to all people who want to make the most of themselves.  The salesman of himself needs to understand his “goods” thoroughly; so as we study the selling process that completes the secret of certain success, we dig into practical psychology a little way now in order to stimulate in you a desire for further exploration of that gold mine of opportunities.

[Sidenote:  Physical Manifestations of Ideas]

The mind depends on the brain, in coordination with the nerves and muscles, to express thoughts.  That is how your inner or “ego” sales-man gets his ideas out of your physical salesman, and shows them to the minds of prospective buyers.  You can make another person conscious of your thoughts only by some perceptible physical manifestation of the idea you wish to convey to him.  Evidently, then, in order to succeed in developing your big sales manhood and in making effective impressions of it on others, you must learn both how to think the ideas of big manhood into your own mind most effectively and how to show them outwardly with masterly skill.  The first process is man development; the second is sales-man-ship, or manhood self-expression for the purpose of controlling the ideas of other men.