_Physiological irritability._ The highly-gifted musician responds physiologically to sound stimuli to a very high degree because he has inherited a genetic constitution which is anatomically and physiologically exceptionally responsive to sound. In other words, quite apart from consciousness of sound or thought of music, his physical organism responds to acoustic stimuli of all kinds which keep nerve and muscle in a state of tension. This tends to create a state of unrest and irritability. Without leading to actual hearing, it may arouse associations of a sort of dreamlike or dramatic nature which may play a very large role in the conscious life. It may create a state of well-being and happy associations, but perhaps more frequently irritation and noxious day-dreaming associations and emotional eruptions. The sounds may come from a squeaking chair, the sizzling of a kettle, the song of a bird, the cry of an infant. Most frequently sounds affecting the organism in this way are inconspicuous and commonplace in the environment; but they may often be strong; such as, the rattling of a train or the chattering in a crowd, of which the musician does not become conscious, although physiologically irritated. _Tonal sensitivity._ All great musicians are highly sensitive to sound in all its elements. A physiological irritability acoustically leads to a profuse awareness of sounds. This sensitive and selective hearing gives the musician a richness of material in the musical medium. He becomes intolerant and rebellious to disturbing sound stimuli which have no such effect upon unmusical persons. To him, the world of sounds has infinite richness of resources for musical pleasure, but equally exceptional resources for the suffering of musical pain.