Each BRAIN PATTERN is created by some particularelement in the environment to which an adaptation has been madefor the good of the species.  The _*state of threshold_ dependsupon the effect made upon the individual by his personal contactswith that particular element in his environment.  The presenceof that element produces in the individual an associative recallof the adaptation of his species--that is, the brain pattern developedby his phylogeny becomes energized to make a specific response.The intensity of the response depends upon the state of threshold--that is, upon the associative recall of the individual'sown experience--his ontogeny.If the full history of the species and of the individualcould be known in every detail, then every detail of thatindividual's conduct in health and disease could be predicted.Reaction to environment is the basis of conduct, of moral standards,of manners and conventions, of work and play, of love and hate,of protection and murder, of governing and being governed, in fact,of all the reactions between human beings--of the entire web of life.To quote Sherrington once more:  "Environment drives the brain,the brain drives the various organs of the body."By what means are these adaptations made? 

What is the mechanism throughwhich adequate responses are made to the stimuli received by the ceptors?We postulate that in the brain there are innumerable patternseach the mechanism for the performance of a single kind of action,and that the brain-cells supply the energy--electric or otherwise--by which the act is performed; that the energy stored in the brain-cellsis in some unknown manner released by the force which activatesthe brain pattern; and that through an unknown property of these brainpatterns each stimulus causes such a change that the next stimulusof the same kind passes with greater facility.Each separate motor action presumably has its own mechanism--brain pattern--which is activated by but one ceptor and bythat ceptor only when physical force of a certain intensityand rate of motion is applied.

 This is true both of the visiblecontacts affecting the nociceptors and of the invisible contactsby those intangible forces which affect the distance ceptors.For example, each variation in speed of the light-producingwaves of ether causes a specific reaction in the brain.For one speed of ether waves the reaction is the perceptionof the color blue; for another, yellow; for another, violet.Changes in the speed of air waves meet with specific responsein the brain patterns tuned to receive impressions through theaural nerves, and so we distinguish differences in sound pitch.If we can realize the infinite delicacy of the mechanisms adaptedto these infinitesimal variations in the speed and intensity ofinvisible and intangible stimuli, it will not be difficult to conceivethe variations of brain patterns which render possible the specificresponses to the coarser contacts of visible environment.Each brain pattern is adapted for but one type of motion,and so the specific stimuli of the innumerable ceptors playeach upon its own brain pattern only.  In addition, each brainpattern can react to stimuli applied only within certain limits.Too bright a light blinds; too loud a sound deafens.