Morgenröte: Gedanken über die moralischen Vorurteile, 1881. Recommended translation: Daybreak: Thoughts on the Prejudices of Morality, ed. Maudemarie Clark and Brian Leiter, trans. R. J. Hollingdale, Cambridge University Press, 1997.

Excerpt:

1. In this book you will discover a ‘subterranean man’ at work, one who tunnels and mines and undermines. You will see him—presupposing you have eyes capable of seeing this work in the depths—going forward slowly, cautiously, gently inexorable, without betraying very much of the distress which any protracted deprivation of light and air must entail; you might even call him contented, working there in the dark. Does it not seem as though some faith were leading him on, some consolation offering him compensation? As though he perhaps desires this prolonged obscurity, desires to be incomprehensible, concealed, enigmatic, because he knows what he will thereby also acquire: his own morning, his own redemption, his own daybreak? . . . He will return, that is certain: do not ask him what he is looking for down there, he will tell you himself of his own accord, this seeming Trophonius and subterranean, as soon as he has ‘become a man’ again. Being silent is something one completely unlearns if, like him, one has been for so long a solitary mole – – –

Online:
Amazon (Recommended Translation)
Nietzsche Source (German, Free Access)
Project Gutenberg (Free Access) [pdf]