Evangelos has asked and it’s a good question, so here’s a brief explanation:
It’s a combination of two images in Nietzsche. The camel comes from “The Three Transformations,” a section of Thus Spoke Zarathustra. He is there describing transformations that the “spirit” must undergo. First it must become a camel. The camel represents austere, ascetic, obedient commitment to moral ideals, especially truthfulness. The camel’s truthfulness though leads the camel eventually to understand the conditional character of morality, that it has no divine origin and that his camel like subservience is not justified.
The camel stage ends when the spirit must become a lion to do what the camel cannot: defy the “Dragon of ‘Thou shalt’” with the counter-answer of “I will,” therewith rejecting the authority of all those who claim that all values are unalterably fixed. The camel’s obediently, reverentially, ascetically moral endeavor of utmost truthfulness itself leads him to discover the responsibility to reject belief in immutable, absolute bases for obedience. Yet if he is to actually reject this precondition of his quintissential activities, the camel must become a different kind of animal, a lion. It is the lion that confronts the “Dragon of Thou Shalt.” The Dragon of Thou Shalt tries to claim that there can be no new values, no moral reimagination but only fixed, preexisting commands. Only the lion has the defiant courage to say No to the Dragon of Thou Shalt.
But the lion’s self-assertive freedom to say no to the old values is not the end. The lion must transform into a child with an innocent ability to say “yes.” Freedom must evolve from the lion’s negativity and rejection, its form as freedom from the sway of another’s law, to an affirmative freedom not characterized in terms of what it opposes. The lion can only be creative negatively as a creative destroyer of the false and as such is always in a dialectical dependence on that which he is no-saying to.
So the lion must become a child: an affirmativeness that has no conscious need to reject anything. Nietzsche describes the child as “innocence and forgetting, a new beginning, a game, a self-propelled wheel, a first movement, a sacred ‘Yes.’” Not continuing to say “no,” the spirit now forgets he ever had to say no. This is a new beginning, in some way distinct from a merely altered continuation. This spirit is not responsive to external determinants, for the law that the camel reverentially obeyed and which the lion summoned its courage reactively to oppose is no longer influential.
In my dissertation I make the claim that “The Three Transformations” encapsulates Nietzsche’s project and his goals. I argue that understanding Nietzsche’s prima facie conflicting remarks often depends on whether he is writing from the perspective of the camel, the perspective of the lion, or the perspective of the child, so to speak. His “camel” remarks are those within the language and assumptions of traditional morality. His “lion” remarks are those which are critically attempting tear down the lies and errors of traditional morality and Christianity. The “child” remarks are those where Nietzsche is valuing positively–sketching and celebrating the various possibilities for a genuinely affirmative new ethics based on an embrace of reality rather than an otherworldly morality’s disdain for this world.
The hammer comes from the subtitle to Twilight of the Idols, “How One Philosophizes With A Hammer.” The hammer to which Nietzsche refers is a tuning fork. The metaphor he employs is that he is striking idols with this tuning fork in order to test them to see what sounds they make. But I also like the other connotations evoked by the image of a hammer. I see it as a tool for smashing idols and a tool for constructively building something better to replace them.