|The greek God Apollo|
In Greek mythology, Apollo and Dionysus are both sons of Zeus. Apollo is the god of the Sun, and also of dreams, and, most importantly that of reason while Dionysus is the god of wine, ecstasy, wildness and intoxication. The ancient Greeks did not consider the two gods to be opposites or rivals. However, Parnassus, the mythical home of poetry and all art, was strongly associated with each of the two gods in separate legends.
The WIKI puts the interplay or dialectic or dynamic tension between these two opposing but complementary principles most aptly indeed:
Apollo is the god of the Sun, and also of dreams, order and measure, and, most importantly that of reason while Dionysus is the god of wine, ecstasy, wildness, frenzy, wild sexual abandon, communal celebration and intoxication. Now, it was pure genius on Nietzsche's part to see the importance of joining the two in a healthy tension or polarity or balance of opposites. For him, true tragedians like Aeschylus and Sophocles (but not Euripides), managed to bring the art of tragic drama to its highest pointr by combining the Apollonian perfection of poetry, reason and diction with the Dionysian energy of music and dance. The true effect of tragedy is to hold both these worlds together in dynamic tension. Now, it is important to state that mythology sees Orpheus as a son of Apollo. Once again the the music of Orpheus, like that of Apollo, is the calm, soothing strains of the lyre.