Almost phenomenal development can be attained by use of the discriminative-restrictive training method.  The minutest distinctions can be perceived if one concentrates his practice for mental growth on the recognition of differences only.  Individuals who have lost one or more senses become extraordinarily adept in detecting contrasts with their other senses.  A normal man, possessed of all his senses, is capable of even greater development of his powers of differentiation.

You know how remarkably a blind man learns to “see” with his fingers and ears.  But need you lose the sense of sight before you can comprehend the lesson of his example to you?  You realize that you appear to lack many essential qualities of success.  Know now that these are all merely dormant in you.  They can be awakened and developed to an extraordinary degree if you train yourself consciously in the discriminative-restrictive use of all your sense tools.  You would do it if you were blind.  It certainly should be much easier to accomplish the desired transformation with your eyes open to aid your other senses.

[Sidenote:  Whatever You Lack Now You Can Develop]

The significance of all this is that you need not be permanently handicapped in your sales-man-ship by any present lack of particular qualifications for success. It makes no difference what you happen to be short of now.  By properly coordinating your brain-mind-muscle sets or centers, and by using all three in the processes of your development, you can make yourself over almost miraculously.  Will power, courage, exact and wise judgment, persistence, patience, rapid thinking, constructive imagination—­any and all qualities you want CAN be developed in you, even though they now seem not to exist.

Your development is limited only by the practically limitless number of unawakened cells in your brain.  Most of your potential mind centers are asleep yet. You can wake up the slumberers with your various sense muscles, and vigorously exercise them into activity for your success.  You have been handicapped because you have been carrying so many “dead-heads” that ought to be working or paying their way.

Remember that growth of any brain-mind center can be begun and continued only by the exercise of the coordinated set of sense muscles in transmitting impressions from outside yourself and in expressing your thoughts.

[Sidenote:  Your Limitless Brain Capacity]

The number of cells in the human brain has been estimated at from six hundred millions to two billions.  The greatest genius who ever lived doubtless had scores of millions of brain cells that remained more or less idle, if not sound asleep, all his life.  Nature has furnished you with a plentiful surplus of grey matter in your head.  Do not be afraid that you will exhaust or tire out your brains by your self-development. Put into your work all the brains you can waken with your various senses.  And keep the alarm clocks wound up.