Up, abysmal thought, out of my depth! I am your cock and dawn, sleepy worm. Up! Up! My voice shall yet crow you awake! Unfasten the fetters of your ears: listen! For I want to hear you. Up! Up! Here is thunder enough to make even tombs learn to listen. And wipe sleep and all that is purblind and blind out of your eyes! Listen to me even with your eyes: my voice cures even those born blind. (Zarathustra, Part 3)

This is  Zarathustra calling up his most “abysmal thought” immediately before he had to go down into the death experience (experience?) required for ‘the convalescent‘:

No sooner had Zarathustra spoken these words than he fell down as one dead and long remained as one dead. (Zarathustra, Part 3)