Abstract
"Twilight of the Idols" plays an important role in Nietzsche’s work, since it represents the opening writing of the philosophical project called "Transvaluation of all values". In that text, Nietzsche aims to sound out the "eternal idols", which means to disclose the inconsistency of the principles of traditional metaphysics. The way Nietzsche addresses the "old truths" in Twilight of the Idols leads back to his early writings, when his theory of knowledge is first outlined, inspired by Schopenhauer as much as neo- and post-Kantian thinkers such as F. Lange and A. Spir. As I shall show, these observations can be compared with Ernst Mach's anti-metaphisical attitude to the ordinary world-conception, insofar as Mach as much as Nietzsche stressed the importance of a historical approach as instrument to enlighten the "prejudices" of traditional scientists or philosophers.