Thus Spoke Zarathustra: A Book For All and None was Nietzsche’s favourite of his creations. It is indeed one of the most fascinating and creative pieces of work in western philosophy.
It presents the journey of Persian prophet Zarathustra, who spends his time in solitude in the mountains for ten years and grows weary of his wisdom, beginning his down-going to humanity to teach them what he has learned. Zarathustra's principal teachings are: the Übermensch (Overman), the Eternal Recurrence and the Will to Power.
The God is dead theme is most famously expressed in Thus Spoke Zarathustra, although it first appeared in The Gay Science. It is commonly misinterpreted. It refers to a historical event in response to the decline of Christianity with the Enlightenment bringing about scientific rationality, representing a crisis in the existing moral values opening the possibility for nihilism. The death of god theme is prevalent throughout the book.