Later authors characterized idolatry in very different terms: the Book of Isaiah is believed to have been composed and revised by different authors in different periods, with chapters 1-39 being composed by the historical prophet Isaiah in the 8th century BCE, chapters 40-55 attributed to "Deutero-Isaiah," an anonymous author writing during the Babylonian captivity of the 6th century BCE, and chapters 56-66 attributed to "Trito-Isaiah," writing after the return from exile. Isaiah 44:6 contains the first unambiguous statement of monotheism, "I am the first and I am the last; beside me there is no God." Isaiah 44:9-10 also contain the first clear declarations of the futility of idolatry and, accordingly, the nonexistence of the other Canaanite gods: "All who fashion idols are nothing, and the things they delight in "do not profit"." and "Who fashions a god or casts an idol that is profitable for nothing?" As Yahwism competed with the other cults of Canaan and became more focused on Yahweh in particular, and eventually to the exclusion of the older Canaanite gods, its conception of idolatry changed as well, paving the way for monotheism.