Heidegger intended to replace metaphysics by a new kind of thought about that which he called 'Sein', but in his works this noun is very far from meaning the act of being such as it has been traditionally conceived by Western philosophy. His explanations as to what he does mean by 'Sein' underline his departure from traditional metaphysics. 'Sein' is no longer to be understood as the act of the things that exist in the eternal world, but as something revealed to the human mind in an esoteric way. The association of this esoteric revelation of 'Sein' With Holderlin's theosophy led Heidegger to put forward a new gnosis organized as a substitute of metaphysics and of Christian theology as well.