The general objective of the thesis is to make a history of Hans Jonas philosophy of initial thought. Its specific objective is to investigate, in the genesis of Jonasian thought, the environments we call (Anti) messianism, anti-fascism and existentialism. Certain aspects of these three environments resemble the Homeric metaphor of Sirens Song: they point to the spread of dogmatic narratives that dangerously corrupt the political environment. Inspired by the Sophist s Platonic strategy, we will try to entrench such corners, thus demarcating the first philosophical attitude of Hans Jonas from his anti-Messianism, his anti-fascism and his existentialism. Our strategy is to present a set of hypotheses and evidence – based on the research of unpublished documents by Hans Jonas Archiv, from Konstanz Universität – that validate the intellectual belonging of Hans Jonas to the above mentioned environments. They also point, in our view, to important further developments in Jonasian philosophy.