His military schooling and participation in the war of 1870-71 probably led to his discovery of a hard and manly quality in himself, and imbued him with an extreme abhorrence of all softness and effeminacy. He turned aside with disgust from the morality of pity in Schopenhauer's philosophy and from the romantic-catholic element in Wagner's music, to both of which he had previously paid homage. He saw that he had transformed both masters according to his own needs, and he understood quite well the instinct of self preservation that was here at work. The aspiring mind creates the helpers it requires. Thus he afterwards dedicated his book, Human, all-too-Human, which was published on Voltaire's centenary, to the "free spirits" among his contemporaries; his dreams created the associates that he had not yet found in the flesh.
The severe and painful illness, which began in his thirty-second year and long made him a recluse, detached him from all romanticism and freed his heart from all bonds of piety. It carried him far away from pessimism, in virtue of his proud thought that "a sufferer has no right to pessimism." This illness made a philosopher of him in a strict sense. His thoughts stole inquisitively along forbidden paths: This thing passes for a value. Can we not turn it upside-down? This is regarded as good. Is it not rather evil?--Is not God refuted? But can we say as much of the devil?--Are we not deceived? and deceived deceivers, all of us?...
And then out of this long sickliness arises a passionate desire for health, the joy of the convalescent in life, in light, in warmth, in freedom and ease of mind, in the range and horizon of thought, in "visions of new dawns," in creative capacity, in poetical strength. And he enters upon the lofty self-confidence and ecstasy of a long uninterrupted production.