Even­tu­ally, with the con­struc­tion of valve in­stru­ments, the in­ter­est for these great, natu­ral main in­ter­vals faded, and the “new sound” com­pos­ers of the 20th cen­tury turned to even finer in­ter­vals of the ma­jor and minor sec­ond – that is, the space be­tween the sev­enth and eighth over­tone, the eighth and ninth over­tone; or the space be­tween the ninth and tenth over­tone, and the tenth and elev­enth over­tone re­spec­tively.

At this point, how­ever, the new com­pos­ers be­gan to intimidate the mu­sic lover; for, even to the un­edu­cated ear, the discrepancy of the “forced marriage” be­tween the mi­cro­cosm and the mac­ro­cosm of mu­sic be­came clear; a marriage, in which the mi­cro­cosm pro­duces shrill dis­so­nances due to the lack of sen­si­tiv­ity of the mac­ro­cosm.

The continu­ous play­ing of tones at too small in­ter­vals causes a friction be­tween their high over­tones, which are too closely spaced, and cre­ates a strange sharpness of shrill dis­so­nances, thus de­stroy­ing the com­pre­hen­sion of the in­ner con­tent of a com­po­si­tion – since they shift the at­ten­tion of the lis­tener, and even that of the mu­si­cian, in­ces­santly from the immanent logic of the com­po­si­tion to the gross com­bat of over­tones. Thus, each over­tone fights its neighbour for su­pe­riority, some­thing we per­ceive as shrill, and reject as un­pleas­ant.

This leads us to twelve-tone mu­sic and to the tech­nique of serial com­po­si­tion of the 20th cen­tury – the so-called avantgarde.

Not that the great clas­sics had been un­able to write in sec­onds or to pro­duce dis­so­nances, but in the mixture of the outer-mu­si­cal mac­ro­cosm and the in­ner-tonal mi­cro­cosm they rather knew the natu­ral limits, which exist as long as the mu­si­cian does not mas­ter the mi­cro­cosm of mu­sic.

There­fore, the great clas­si­cal com­pos­ers from Bach to Wagner only ap­proached, but never crossed, the bor­der to dis­har­mony, and thus cre­ated mostly har­mo­ni­ous mu­sic.

This in­di­cates that they were guided by their natu­ral in­ner hear­ing, and that to them a lined sheet of paper was not a draw­ing board for the con­struc­tion of mu­sic.
With per­fect con­fi­dence the great clas­si­cal mu­si­cians sim­ply brought to paper what they heard within.