The article analyzes Heidegger’s view on φύσις and αλήθεια. It focuses primarily on explicating the meaning of the ancient term “λήθη”. There follows and attempt to define the philosophical idea of αλήθεια. Heidegger seeks the sense of this word in myth and he is concerned with the relevance of the thought of Heraclitus and Parmenides. The metaphor of fire is at the center of his philosophical interpretation of the world. It reveals the mystery of Being because this is a struggle to show things.