Then it describes, in progressive stages, how the earth came to be habitable, how various life forms came into existence, and how humans appeared on the scene ​ — as well as the purpose of it all.
فهما يعودان بنا في الزمن مليارات السنين الى « البدء » حين خُلق كوننا المادي ،‏ بما فيه المجرات والنجوم والارض .‏