In 1872 Friedrich Nietzsche published The Birth of Tragedy out of the Spirit of Music. He later re-released it with a preface in 1886. Raymond Geuss and Ronald Speirs explain the book as “an attempt to use theses derived from Schopenhauer and Wagner (in conjunction with an interpretation of archaic Greece) to sketch a new form of tragic culture.”
In particular, Nietzsche adopted the pessimism of Schopenhauer (life is not worth living) and the artful mysticism of Wagner (aesthetics justifies the world). Thus The Birth of Tragedy aims to justify existence, given the reality of pessimism, that the world lacks any sort of essential goodness. In Nietzsche’s words, “the world is justified (gerechtfertigt) only as an aesthetic phenomenon.” For Nietzsche in his The Birth of Tragedy, that justification involves a union between a primary Dionysiac energy and the illusion or Schein of Apoliticism.
Apoliticism (words) and the Dionysiac (music) unite in Greek tragedy because the former provides the Schein or illusion that our lives have meaning through epic speech, individuality, and boundaries for life. By contrast, the Dionysiac lacks individuality, is full of music and danger because it points to reality: “our individual identity is an illusion.”
Uniting Apollo and Dionysius together, Greek tragedy, claims Nietzsche, makes life tolerable due to the illusion (Schein) that Apoliticism brings through its artifices of epic speech and individualism. Nietzsche believes tragedy came out of the early noble Greek culture, one which in the fifth century BC began falling apart.
A symptom of this decay is Socratism—the illusion that reason can overcome societal ills (see Twilight of the Idols). Christianity is a later symptom of this decadence (see The Antichrist). But they are attractive illusions because the alternative to Schein is death.
By the time Nietzsche writes his 1886 preface to The Birth of Tragedy, he modifies his earlier view somewhat. He can speak of “a pessimism of strength.” He means something like this. Although life is not worth living (pessimism), we still pursue life and instinct “from an abundance of existence.” But he apparently retains his pessimistic perspective to a large degree. He speaks of himself “as an advocate of life” who formed a “doctrine and counter-evaluation of life” called “Dionysiac.”
This doctrine importantly is “artistic” and rejects supremely Christianity. The Dionysiac could just as well be called “the Antichrist.” To understand how Nietzsche advocates for life, it is worth understanding how Nietzsche views Christianity as carrying on the Socratic, rational, and moral way of life that really evinces “hostility to life” and a “will to decline.”
Consider this long criticism of Christianity as a form of nihilism and Nietzsche’s affirmation of the Dionysiac:
In truth there is no greater antithesis of the purely aesthetic exegesis and justification of the world, as taught in this book, than the Christian doctrine which is, and wants to be, only moral, and which, with its absolute criteria (its insistence on god's truthfulness, for example) banishes art, all art, to the realm of lies, and thus negates, damns and condemns it. Behind this way of thinking and evaluating, which is bound to be hostile to art if it is at all genuine, I had always felt its hostility to life, a furious, vengeful enmity towards life itself; for all life rests on semblance, art, deception, prismatic effects, the necessity of perspectivism and error. From the very outset Christianity was essentially and pervasively the feeling of disgust and weariness which life felt for life, a feeling which merely disguised, hid and decked itself out in its belief in 'another' or 'better' life. Hatred of the world', a curse on the passions, fear of beauty and sensuality, a Beyond, invented in order better to defame the Here-and-Now, fundamentally a desire for nothingness, for the end, for rest, for the 'Sabbath of Sabbaths' — all this, together with the determination of Christianity to sanction only moral values, seemed to me the most dangerous and uncanny of all possible forms of a 'will to decline', at the very least a sign of the most profound sickness, tiredness, distemper, exhaustion, impoverishment of life — for before the court of morality (especially Christian, which is to say unconditional, morality) life must constantly and inevitably be proved wrong because life is essentially something amoral; life must eventually, crushed by the weight of contempt and the eternal 'no!', be felt to be inherently unworthy, undeserving of our desire. Morality itself — might it not be a 'will to negate life', a secret instinct for annihilation, a principle of decay, belittlement, calumny, the beginning of the end? And consequently the greatest danger of all? Thus my instinct turned against morality at the time I wrote this questionable book; as an advocate of life my instinct invented for itself a fundamentally opposed doctrine and counter-evaluation of life, a purely artistic one, anti-Christian one. What was it to be called? As a philologist and man of words I baptized it, not without a certain liberty — for who can know the true name of the Antichrist? — by the name of a Greek god: I called it Dionysiac.
The key to understanding this long argument of Nietzsche is to see Christianity as an illusory medicine for society’s ills through revelation and morality. But these emphases end up showing a decadence, a sort of pathology, since it suppresses the artistic, the Dionysiac. What exactly was Nietzsche’s vision for the Dionysiac? The only real answer is to read his Thus Spoke Zarathustra where the prophet of the Dionysiac, Zarathustr, speaks.