Man is a metaphysical animal. He does not live by bread alone, nor by bed alone, and he does not scratch only where it physically itches. He also scratches where he feels the metaphysical itch, the tormenting lust to know the ultimate why and wherefore. And where is that punctum pruriens located? What is it that arouses his intellectual eros?
. . . das Böse, das Uebel und der Tod sind es, welche das philosophische Erstaunen qualificiren und erhöhen: nicht bloß, daß die Welt vorhanden, sondern noch mehr, daß sie eine so trübsälige sei, ist das punctum pruriens der Metaphysik, das Problem, welches die Menschheit in eine Unruhe versetzt, die sich weder durch Skepticismus noch durch Kriticismus beschwichtigen läßt.
. . . it is wickedness, evil, and death that qualify and intensify philosophical astonishment. Not merely that the world exists, but still more that it is such a miserable and melancholy world, is the punctum pruriens of metaphysics, the problem awakening in mankind an unrest that cannot be quieted either by scepticism or criticism. (Schopenhauer, WWR II, 172, tr. Payne)