Evidently, too, a weak, undeveloped brain center would be incapable of receiving strong mental impulses from its coordinated mind center, and of transmitting them in full strength to the particular muscles governed by that mind center.  This is why, if a man’s brain center of courage is undeveloped, even the most courageous thoughts will not make his body act bravely.  His legs may run away against his will to fight.  The physical instrument of his mind (his brain), and also certain associated sets of muscles, must be sufficiently exercised in the action of courage to build up within him the physical structure of fearlessness that will be instantly responsive to a mental attitude of bravery.

[Sidenote:  Right Exercise for Development]

If for any reason the brain instrument is weak or undeveloped, it can handle only weakly either in-coming messages to the ego from the senses, or out-going impulses from the mind to the muscles.  So, because of this undeveloped brain instrument, the full capability of neither the inner nor the outer man can be built up and put to use.  Obviously, therefore, if one is ambitious to succeed, he needs to know and to practice the coordinated mind-brain-muscle exercises that will increase the quantity and better the quality of his man capacity.  Since he is a “many-minded, many-bodied” man, general physical and mental exercise will not develop the particular qualities required to assure his success.  Each and every mind-brain-muscle set must be built up individually by specific exercises which strengthen that particular unit of the multiplex man.  Then, of course, all his units should be taught to work together to make his success certain with his all-around capability fully developed and coordinated.

[Sidenote:  The Discriminative-Restrictive Method]

Luther Burbank worked out “discriminative-restrictive” methods of growth that may be applied as successfully to men as to plants.  He could not have built up the ability of a prune tree to produce delicious fruit if he had not fed into the tree structure, or instrument of production, a sufficient quantity and high quality of the particular plant foods of deliciousness.  He restricted his experimental prune trees to the development of specific delicious qualities, by giving them no food except that discriminatively selected for his purpose.  That is, he made them develop in one way and in one way only, when he was making a particular test.

Similarly, as has been stated before, you can develop the specific man qualities you need to succeed.  You must feed to a particular mind center, through the related brain center, selected sense impressions.  These can come only from the coordinated set of muscles governed by that mind-brain center.  Then you should exercise the specific brain center and set of muscles in the production of mental reflexes, or the mind fruit.  Acts of courage, for example, are the fruit of brave thoughts.