Ah. I follow. [Alucard will concede his perspective is not the correct one here. He doesn't like the religion involved, and he's reducing it only to myth, rather than playing into the story being real. Sypha would have known better.]

Tradition holds that the first five books of the Hebrew Bible - or Old Testament so far as the Christians refer to it - was written by Moses. He was a prophet and chosen by their god to lead them out of enslavement. These books are divinely inspired. The author, in this case, is not a witness. It is given to him by his god to put down on the page. So while logically I would say it was an oral history developed and then written down, the answer within the context of the faith is a prophet in communication with the divine.