Friedrich Nietzsche 
Beyond Good and Evil 
"That which does not kill us makes us stronger."

Nietzsche is a true icon and his name is revered and sometimes reviled by those with more than a passing interest in his field. Beyond Good And Evil expands on his previous work Thus Spoke Zarathustra and moves to criticise previous philosophers who had a clear delineation between good man and evil man rather than, as Nietzsche argues that they are just different expressions of the same being. Nietzsche is not afraid to argue and his work is outstanding whatever your own viewpoint.