This characterizes the dichotomy between the Dionysian and Apollinian world views. Nietzsche sees this sublime metaphysical illusion as a necessary presupposition for any scientific thinking. The Socratic culture ultimately will realize that its belief in itself, its eternal optimistic outlook, is doomed to fail. Our image of Socrates is one that sees him as a man who overcame his fear of existence through reason and knowledge. Essentially, the project of theoretical man contains within its own logic the necessity of its own destruction and the ultimate primacy of art- the only true justification for life.
Art alone makes life comprehensible and justifiable.