He began to actually write Thus Spake Zarathustra in February of 1883 but the germ of the idea behind it had been developing in his mind for some eighteen months. In Ecce Homo it is related how the idea occured to him in August 1881 and remained in gestation. When he came to actually write based upon his initial idea Nietzsche felt that he was actually inspired - as one of the most intriguing quotes from Ecce Homo suggests:-
"One hears but one does not seek; one takes - one does not ask who gives; a thought flashes up like lightning, it comes of necessity and unfalteringly formed".
His fundamental contention was that traditional values (represented primarily by Christianity) had lost their power in the lives of individuals. He expressed this in his proclamation "God is dead."
Since God is dead Nietzsche sees the necessity for the emergence of the Übermensch, the Superman or overman, who is to replace God.
The first of the quotes attributed to Zarathustra is:-
"I teach you the Superman. Man is something that should be overcome. What have you done to overcome him? All creatures hitherto have created something beyond themselves: and do you want to be the ebb of the great tide, and return to the animals rather than overcome man? What is the ape to men? A laughing stock or a painful embarassment. And just so shall man be to the Superman: a laughing stock or a painful embarassment".
The context in which Supermen are to be judged to be such is implied by Neitzsche's previous works. He maintained that all human behavior is motivated by the will to power. In its positive sense, the will to power is not simply power over others, but the power over oneself that is necessary for creativity....