Genesis 6, 1-4 is usually regarded as an enigmatic text because of the expressions it contains: “son of God”, nephilim and gibborim. Its relationship to the tale of the flood is often discussed in connection with the mythological sources it reveals. Most of the translations beginning with the Septuagint, like the interpretations derived from philosophical tradition, take the reader back to a very recognizable network of mythological connotations which misses a subtle working carried out by the text, both before and after this passage, and which is the only thing that makes it possible to understand its true intentions. The present study is devoted to the reconstruction of this network.