There is, he thinks (in BT and for a short time afterwards), something so striking about the difference between the pleasure we gain from the visual arts and epic poetry, on the one hand, and that which is vouchsafed us by music and tragic drama (which is properly speaking only that which is set to music) on the other, that we are forced to give an account of the fundamentally different drives which animate them. It is in this way that he comes to postulate the existence of the Apolline and the Dionysiac.
