"We will have achieved much for the study of aesthetics when we come, not merely to a logical understanding, but also to the immediately certain apprehension of the fact that the further development of art is bound up with the duality of the Apollonian and the Dionysian, just as reproduction depends upon the duality of the sexes, their continuing strife and only periodically occurring reconciliation. We take these names from the Greeks who gave a clear voice to the profound secret teachings of their contemplative art, not in ideas, but in the powerfully clear forms of their divine world."
"With those two gods of art, Apollo and Dionysus, we link our recognition that in the Greek world there exists a huge contrast, in origins and purposes, between visual (plastic) arts, the Apollonian, and the non-visual art of music, the Dionysian. Both very different drives go hand in hand, for the most part in open conflict with each other and simultaneously provoking each other all the time to new and more powerful offspring, in order to perpetuate for themselves the contest of opposites which the common word 'Art' only seems to bridge, until they finally, through a marvelous metaphysical act, seem to pair up with each other and, as this pair, produce Attic tragedy, just as much a Dionysian as an Apollonian work of art."
"In order to get closer to these two instinctual drives, let us think of them next as the separate artistic worlds of dreams and of intoxication, physiological phenomena between which we can observe an opposition corresponding to the one between the Apollonian and the Dionysian."
(Friedrich Nietzsche, excerpt from The Birth of Tragedy)